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: Physiology
[{'content': 'One patient with chronic diarrhea noticed improvement in symptoms after prolonged fasting. He is most probably suffering from: \nSelect and explain. \nA. Inflammatory bowel disease, B. IBS, C. Diarrhea secondary to lactose malabsorption, D. Enterotoxin-induced diarrhea.', 'role': 'user'}, {'content': "Answer: C \nExplanation: The demonstration of the effect of prolonged (>24 h) fasting on stool output can be very effective to differentiate osmotic and secretory diarrhea. A secretory (enterotoxin-induced traveler's) diarrhea is not affected by prolonged fasting. Diarrhea secondary to lactose malabsorption would cease during a prolonged fast. Ref: Harrison, E-18, P-2460.", 'role': 'assistant'}]