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: Pharmacology
Which of the following drug is alpha–glucosidase inhibitor ? 
Select and explain. 
A. Pioglitazone, B. Miglitol, C. Metformin, D. Nateglinide
B: Miglitol
Answer: B: Miglitol 
Explanation: None