This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intestine, Subject name: Medicine
Which of the following is produced by Carcinoid tumor? 
Select and explain. 
A. G.A.B.A, B. Serotonin, C. Epinephrine, D. Nor-epinephrine
B: Serotonin
Answer: B: Serotonin 
Explanation: Ans. (b) SerotoninRef : Harrison 19th ed. / 564-65* Argentaffin cells in Carcinoid produce 5HT derivatives like serotonin. Epinephrine and norepinephrine are produced by chromaffin cells which are seen in phaeochromocytoma.