The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Heart of controlled trial?   (A) Blinding   (B) Experiment   (C) Randomization   (D) Intervention
['(C) Randomization <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Blinding \n (B) Experiment \n (C) Randomization \n (D) Intervention <> possible answers', '  Heart of controlled trial? <> context@']