The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Cross-sectional studies are carried on   (A) Same individuals but of same age   (B) Different individuals but of same age groups   (C) Same individuals at different ages   (D) Different individuals of different age groups
['(D) Different individuals of different age groups <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Same individuals but of same age \n (B) Different individuals but of same age groups \n (C) Same individuals at different ages \n (D) Different individuals of different age groups <> possible answers', '  Cross-sectional studies are carried on <> context@']