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: Medicine
[{'content': 'Drug used in irritable bowel syndrome with constipation \nSelect and explain. \nA. Lubiprostone, B. Fedotozine, C. Loperamide, D. Mebeverine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Lubiprostone (CL- channel activator).', 'role': 'assistant'}]