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': 'Gastric motility is increased in: \nSelect and explain. \nA. Acid in duodenum, B. Tryptophan in duodenum, C. Distension of stomach, D. Fatty food in stomach', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Acid in duodenum', 'role': 'assistant'}]