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
Insulinoma true area) Present in pancreasb) Mostly malignantc) surgical therapy indicated if diagnosedd) Present in Bile 
Select and explain. 
A. a, B. bc, C. ac, D. b
C: ac
Answer: C: ac 
Explanation: Only about 10-15% of insulinomas are malignant (whereas all other endocrine tumors of pancreas are usually malignant).