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: Medicine
Most important investigation for diagnosis of Zollinger Ellison-syndrome is - 
Select and explain. 
A. Ca++ infusion test, B. Secretin injection test, C. ACTH stimulation test, D. Steroid assay
B: Secretin injection test
Answer: B: Secretin injection test 
Explanation: None