Which medication is an oral hypoglycemic agent that stimulates insulin release?

Choice A rationale Metformin is a biguanide that works by decreasing hepatic glucose production and improving insulin sensitivity in peripheral tissues. It does not stimulate insulin release from the pancreas; rather, it makes the body's existing insulin more effective. Choice B rationale Glyburide is a sulfonylurea oral hypoglycemic agent. Its primary mechanism of action is to stimulate the beta cells of the pancreas to release more insulin. This makes it effective in lowering blood glucose levels, but also carries a risk of hypoglycemia. Choice C rationale Pioglitazone is a thiazolidinedione (TZD) that acts on peroxisome proliferator-activated receptor gamma (PPAR-γ) to increase insulin sensitivity in muscle and adipose tissue. It does not stimulate the release of insulin but rather addresses insulin resistance. Choice D rationale Acarbose is an alpha-glucosidase inhibitor. It works in the intestine to delay the digestion of carbohydrates. This slows down glucose absorption after a meal, reducing the postprandial blood glucose spike. It does not affect insulin secretion.