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: Surgery
Most common functional tumors of endocrine pancreas? 
Select and explain. 
A. Vipoma, B. Gastrinoma, C. Glucagonoma, D. Somatostatinoma
B: Gastrinoma
Answer: B: Gastrinoma 
Explanation: Answer- B. GastrinomaInsulinoma is the most common functional tumour but if that wasnt there in the optios then gastrinoma is the next answer.