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
Which of the following is the MOST common endocrine tumour of pancreas? 
Select and explain. 
A. Insulinoma, B. Gastrinoma, C. VIPoma, D. Glucagonoma
A: Insulinoma
Answer: A: Insulinoma 
Explanation: Insulinomas are the most common pancreatic endocrine neoplasms. Patients present with a typical clinical syndrome known as Whipple's triad which consists of symptomatic fasting hypoglycemia, serum glucose level Lab evaluation shows elevated insulin and C-peptide levels. Insulinomas are usually localized with CT scanning and EUS. They are evenly distributed throughout the head, body, and tail of the pancreas. 90% of insulinomas are benign only 10% of it is malignant. 90% are sporadic and only 10% are associated with the MEN1 syndrome. Ref: Schwaz's Principles of Surgery, 9e chapter 33.