This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
[{'content': 'Nitroglycerine exes beneficial effects in classical angina pectoris primarily by: \nSelect and explain. \nA. Increase in total coronary blood flow, B. Redistribution of coronary blood flow, C. Reduction of cardiac preload, D. Reduction of cardiac afterload', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (Ref: KDT 6/e p523) Mechanism of action nitrates in classical angina is reduction in preload (due to venodilation) and in variant angina is coronary vasodilation.', 'role': 'assistant'}]