This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'In essential hypertension the drug prescribed with least cardiovascular effect - \nSelect and explain. \nA. Clonidine, B. Alpha blocker, C. Beta blocker, D. ACE inhibitor', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]