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 Argentaffi- noma of ileum? 
Select and explain. 
A. G.A.B.A., B. Serotonin, C. Epinephrine, D. Nor-epinephrine
B: Serotonin
Answer: B: Serotonin 
Explanation: Ans. 'b' i.e. Serotonin o Argentaffin cells of the carcinoid produce serotonin.o The metabolites of serotonin are 5HIAA and are used in the diagnosis of carcinoid syndrome.