This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
Carcinoid tumor is diagnosed by. 
Select and explain. 
A. Urinary 5 HIAA, B. Chromogranin A, C. Neuron specific enolase, D. Urinary 5 Hydroxy tryphtophan
A: Urinary 5 HIAA
Answer: A: Urinary 5 HIAA 
Explanation: Ans. (a) Urinary 5HIAARef: Bailey 27th edition, Page 1251* Most common used investigation to diagnose carcinoid tumor is 24 hours urinary 5HIAA* IOC to localize the tumor is DOTATATE scan