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: Pharmacology
[{'content': 'Which of the following statements about hydralazine is not true ? \nSelect and explain. \nA. It causes direct relaxation of the blood vessels, B. It causes dilatation of both arteries and veins, C. Postural hypotension is not a common problem, D. It increases plasma renin activity', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]