**Core Concept**
Alpha-glucosidase inhibitors are a class of oral antidiabetic drugs that work by inhibiting the enzyme alpha-glucosidase, which breaks down carbohydrates into simple sugars in the small intestine. This mechanism helps to delay the absorption of glucose, thereby reducing postprandial blood glucose levels.

**Why the Correct Answer is Right**
The correct answer is an alpha-glucosidase inhibitor that works by competitively inhibiting the enzyme alpha-glucosidase, which is responsible for breaking down disaccharides like sucrose and maltose into glucose and fructose. This inhibition delays the absorption of glucose into the bloodstream, reducing the peak postprandial glucose levels. By slowing down glucose absorption, alpha-glucosidase inhibitors help to control blood glucose levels in patients with diabetes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a biguanide, a different class of oral antidiabetic drugs that work by decreasing glucose production in the liver.
**Option B:** This option is incorrect because it is a sulfonylurea, a class of oral antidiabetic drugs that work by stimulating insulin release from the pancreatic beta cells.
**Option C:** This option is incorrect because it is a thiazolidinedione, a class of oral antidiabetic drugs that work by increasing insulin sensitivity in peripheral tissues.

**Clinical Pearl / High-Yield Fact**
Alpha-glucosidase inhibitors can cause gastrointestinal side effects like flatulence and diarrhea due to the accumulation of undigested carbohydrates in the colon.

**Correct Answer: C. Acarbose. Acarbose is an alpha-glucosidase inhibitor used in the management of type 2 diabetes mellitus.**