This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'Nitroglycerine exes beneficial effect 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: nitrates are vasodilators mainly acting on the veins only. hence they are venous dilators therefore decrease the preload on the hea where as aerial dilators like hydralazine decrease the after load. Ref: KD Tripathi 8th ed.', 'role': 'assistant'}]