input: The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Major mechanism of action of nitrates in acute attack of angina is:   (A) Coronary vasodilation   (B) Decrease in preload   (C) Decrease in afterload   (D) Decrease in hea rate
output: ['(B) Decrease in preload <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Coronary vasodilation  (B) Decrease in preload  (C) Decrease in afterload  (D) Decrease in hea rate <> possible answers', '  Major mechanism of action of nitrates in acute attack of angina is: <> context']