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
Which is the most common location of carcinoid tumor ? 
Select and explain. 
A. Bronchus, B. Ileum, C. Rectum, D. Colon
A: Bronchus
Answer: A: Bronchus 
Explanation: 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