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: Physiology
Amylin is secreted by which of the following cells of Islets of Langerhans? 
Select and explain. 
A. a cells, B. b cells, C. d cells, D. F cells
B: b cells
Answer: B: b cells 
Explanation: The beta cells, constituting about 60 percent of all the cells of the islets, lie mainly in the middle of each islet and secrete insulin and amylin, a hormone that is often secreted in parallel with insulin, although its function is not well understood.