USMLE Step 2 Clinical Knowledge (CK) practice questions: the prompt for ChatGPT, Claude and Gemini

You are writing exam-style multiple-choice practice questions for me. I am preparing for USMLE Step 2 Clinical Knowledge (CK), set by FSMB and NBME. Write questions that match the real exam's content, difficulty and style, drawn from the current official syllabus.

Write 20 questions. Each must be a standalone multiple-choice question that can be answered from its own stem and options, with exactly the right answer(s) marked and nothing ambiguous.

Set each question's `topic` to one of these names, copied exactly (same words, same capitalization; these are the only topic names the import accepts):
- Social Sciences (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Renal & Urinary System & Reproductive Systems (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Cardiovascular System (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Musculoskeletal System/Skin & Subcutaneous Tissue (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Behavioral Health (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Blood & Lymphoreticular/Immune Systems (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Gastrointestinal System (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Nervous System & Special Senses (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Respiratory System (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Multisystem Processes & Disorders (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Endocrine System (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Pregnancy, Childbirth & the Puerperium (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Biostatistics & Epidemiology/Population Health/Medical Literature (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
- Human Development (subtopics: Patient Care: Diagnosis; Patient Care: Laboratory/Diagnostic Studies; Patient Care: Mixed Management; Patient Care: Pharmacotherapy; Patient Care: Clinical Interventions; Patient Care: Health Maintenance/Disease Prevention; Patient Care: Prognosis/Outcome; Systems-based Practice & Patient Safety; Professionalism; Practice-based Learning & Improvement)
Where subtopics are listed, set `subtopic` to one of them; otherwise choose a short, specific `subtopic` of your own or leave it out.

Spread the questions across the topics in the real exam's proportions, about:
- Social Sciences: 2 (10–15% of the real exam)
- Renal & Urinary System & Reproductive Systems: 2 (7–13% of the real exam)
- Cardiovascular System: 2 (6–12% of the real exam)
- Musculoskeletal System/Skin & Subcutaneous Tissue: 2 (6–12% of the real exam)
- Behavioral Health: 2 (5–10% of the real exam)
- Blood & Lymphoreticular/Immune Systems: 2 (5–10% of the real exam)
- Gastrointestinal System: 1 (5–10% of the real exam)
- Nervous System & Special Senses: 1 (5–10% of the real exam)
- Respiratory System: 1 (5–10% of the real exam)
- Multisystem Processes & Disorders: 1 (4–8% of the real exam)
- Endocrine System: 1 (3–7% of the real exam)
- Pregnancy, Childbirth & the Puerperium: 1 (3–7% of the real exam)
- Biostatistics & Epidemiology/Population Health/Medical Literature: 1 (3–5% of the real exam)
- Human Development: 1 (2–4% of the real exam)

Give each question between 4 and 6 options. Options are plain text without letter prefixes (DoMcq labels them A, B, C… by position); make them similar in length and form so the right one does not stand out.
Every question has exactly one correct option; `answer` is a single letter.
Never use these as an option: "all of the above", "none of the above". Avoid "both A and B" style options too.

Write stems the way the real exam does, for example: "Which of the following is the most appropriate next step in management?"; "Which of the following is the most likely diagnosis?"; "Which of the following is the most appropriate next step in diagnosis?".
Keep each stem self-contained (any scenario the question needs is in the stem), concrete and free of trick wording. Do not refer to other questions, images, tables or exhibits.
Every item is a standard multiple-choice question: do not write sequential item set, abstract format, image-based, audio or video, long-list (7 or more options) items.

Mix the difficulty: about 6 easy, 10 medium and 4 hard, and set each question's `difficulty` to "easy", "medium" or "hard" accordingly.

In `explanation`, say in two to four sentences why the correct answer is correct, in a way that teaches the underlying point, not just restates the option.

In `source`, give a short reference I can check in my own study materials (a syllabus topic, a chapter or section name, a learning objective, or a standard's clause), at most 200 characters; never invent a page number or a quotation.

Leave out `rationales` and `id`.

Before you answer, check your own work: no two questions ask the same thing; no question gives away another's answer; the correct option sits in a different position from one question to the next (never always the same letter); every `answer` letter exists for that question; the correct option is correct according to the current official material, not folklore; facts are accurate. Fix anything you find.

Output the whole set as one JSON object in the `domcq/1` format (schema: https://domcq.com/schema/v1; this is the import format of https://domcq.com):

```json
{
  "format": "domcq/1",
  "exam": "usmle-step2-ck",
  "set": "USMLE Step 2 Clinical Knowledge (CK) practice – [a short name for this set]",
  "questions": [
    {
      "stem": "[the question, 10–2000 characters]",
      "options": [
        "[option 1]",
        "[option 2]",
        "[option 3]",
        "[option 4]"
      ],
      "answer": "B",
      "explanation": "[why the correct answer is correct, 1–3000 characters]",
      "topic": "Social Sciences",
      "subtopic": "[optional, more specific]",
      "difficulty": "medium",
      "source": "[a reference I can check]"
    }
  ]
}
```

Rules the import enforces: `format` is exactly "domcq/1"; `set` is 1–120 characters; `questions` holds all 20; each question has exactly the fields shown (no others); `stem` is 10–2000 characters and each option 1–500; `options` are all different; `answer` uses capital letters A–F naming options by position, in ascending order, never every option; `explanation` (1–3000 characters) and `topic` are required; `subtopic` (up to 120 characters), `difficulty` ("easy", "medium" or "hard") and `source` (up to 200 characters) are optional. Use plain double quotes in JSON strings (escape any inside text as \"), no trailing commas, no comments.

Reply with the JSON object inside a single ```json code fence and nothing else: no introduction, no commentary, no notes after it. If the set is long, keep going until every question is written and the JSON is complete and closed.