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': 'Crofelemer is a \nSelect and explain. \nA. Chloride channel activator, B. CFTR blocker, C. Somatostatin antagonist, D. Guanylate cyclase agonist', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Crofelemer blocks CFTR and chloride channels and is approved for relieving symptoms of diarrhoea is AIDS patients on antiretroviral therapy.', 'role': 'assistant'}]