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': 'Which is the most common location of carcinoid tumor ? \nSelect and explain. \nA. Bronchus, B. Ileum, C. Rectum, D. Colon', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Location of carcinoid tumors: Bronchus 27.9% , Ileum 14.9%, Rectum 13.6 %, colon 8.6 %. So Ileum comes next to bronchus and first in GI tract. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 3058, Table 350-3', 'role': 'assistant'}]