This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
Zollinger- Ellison syndrome is due to increased secretion of 
Select and explain. 
A. Gastrin, B. Secretin, C. VIP, D. Cholecystokinin
A: Gastrin
Answer: A: Gastrin 
Explanation: Gastrinoma (Zollinger-Ellison syndrome) is a condition that includes:Fulminating ulcer diathesis in the stomach, duodenum or atypical sites; Recurrent ulceration despite 'adequate' therapy; and Non-beta islet cell tumours of the pancreas (gastrinoma)Ref: Bailey and Love 27e pg: 850