This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
Which of the following endocrine tumors is most commonly seen in MEN I ? 
Select and explain. 
A. Insulinoma, B. Gastrinoma, C. Glucagonoma, D. Somatotrophinoma
B: Gastrinoma
Answer: B: Gastrinoma 
Explanation: In MEN 1 : * Gastrinoma (>50%) * Insulinoma (10-30%) * Glucagonoma (<3%) * Somatotrophinoma (25%) Reference : page 2336 Harrison's Principles of Internal Medicine 19th edition