This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'Which of the following statements about hydralazine is not true \nSelect and explain. \nA. It causes direct relaxation of blood vessels, B. It causes detection of both aerial and venous, C. Postural hypotension is not a common problem, D. It increases plasma renin activity', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Hydralazine is a predominant aerial dilator that relaxes blood vessels by nitric oxide and opening potassium channels. There is compensatory increase in plasma renin activity with all vasodilators. Postural hypotension is predominantly caused by dilatation of veins and is not a significant feature of hydralazine', 'role': 'assistant'}]