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': 'All are true about guanithidine except \nSelect and explain. \nA. It prevents exocytocis of norepinephrine, B. Used for treatment of erectile dysfunction, C. Side Effects include diarrhoea, D. No CNS related effects are seen with its use', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Refer kK sharma 2/195 guanithidine Acts by inhibiting exocytosis of norepinephrine Does not cross blood brain barrier Postural hypotension diarrhoea and erectile dysfunction are the most common adverse side effects', 'role': 'assistant'}]