This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hepatobiliary and Pancreatic Sx, Subject name: Surgery
Most common functional neuroendocrine tumor of pancreas in MEN1: 
Select and explain. 
A. Glucagonoma, B. Gastrinoma, C. VIPoma, D. Somatostatinoma
B: Gastrinoma
Answer: B: Gastrinoma 
Explanation: NEURO ENDOCRINE TUMORS (NET) OF PANCREAS M/c Neuroendocrine tumor (NET): Non- functional (PPoma) M/c functional Neuroendocrine tumor: Insulinoma M/c functional & malignant NET in MEN 1: Gastrinoma. MC Functional Enteropancreatic NET in MEN 1 - Gastrinoma > Insulinoma SRS- Somatostatin receptor scintigraphy- IOC for All of the neuroendocrine tumors except Insulinoma