**Core Concept**
The question is testing the understanding of the mechanism of action of various antidiabetic drugs, specifically those that target insulin secretion and sensitivity. Increasing insulin secretion is a key therapeutic goal in the management of type 2 diabetes mellitus.

**Why the Correct Answer is Right**
Rosiglitazone is a thiazolidinedione (TZD) that acts by increasing insulin sensitivity, not by increasing insulin secretion. It binds to peroxisome proliferator-activated receptor gamma (PPAR-γ) in adipocytes, which enhances the transcription of genes involved in glucose uptake and storage. This leads to increased glucose uptake in peripheral tissues, thereby reducing blood glucose levels. In contrast, the other options directly increase insulin secretion.

**Why Each Wrong Option is Incorrect**
**Option A:** Exenatide is a glucagon-like peptide-1 (GLP-1) receptor agonist that stimulates insulin secretion from the pancreas in a glucose-dependent manner. This means that insulin secretion is only increased when blood glucose levels are high.
**Option B:** Saxagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that increases the levels of incretin hormones, such as GLP-1, which in turn stimulate insulin secretion.
**Option D:** Glipizide is a sulfonylurea that acts by closing ATP-sensitive potassium channels in pancreatic beta cells, leading to depolarization and insulin secretion.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that thiazolidinediones like rosiglitazone can cause fluid retention and increased risk of heart failure, especially in patients with pre-existing cardiovascular disease. This is an important consideration when selecting antidiabetic medications.

**✓ Correct Answer: C. Rosiglitazone**