input: The following are multiple choice questions (with answers) about medical knowledge.   **Question:** A researcher wants to (to a study of blood levels of lipids among people who smoke and those who do not. But he is now concerned that the smokers might differ from non-smokers in their diet, exercise, etc as well. This concern is known as:   (A) Recall bias   (B) Information bias   (C) Selection bias   (D) Interviewer bias
output: ['(C) Selection bias <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Recall bias  (B) Information bias  (C) Selection bias  (D) Interviewer bias <> possible answers', '  A researcher wants to (to a study of blood levels of lipids among people who smoke and those who do not. But he is now concerned that the smokers might differ from non-smokers in their diet, exercise, etc as well. This concern is known as: <> context']