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': 'Lubipristone is a \nSelect and explain. \nA. Enkephalinase inhibitor, B. Guanylyl cyclase agonist, C. Chloride channel activator, D. 5HT4 agonist', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Lubipristone is a chloride channel activator used in treatment of IBS (Irritable bowel syndrome) with constipation.', 'role': 'assistant'}]