**Core Concept**
Insulin, a hormone produced by the beta cells of the pancreas, plays a crucial role in glucose metabolism by stimulating the uptake and storage of glucose in various tissues. This is achieved through the activation of multiple enzymes involved in glycolysis, glycogen synthesis, and fatty acid synthesis.

**Why the Correct Answer is Right**
Pyruvate carboxylase is a key enzyme in gluconeogenesis, the process of generating glucose from non-carbohydrate sources. Insulin actually inhibits gluconeogenesis by reducing the activity of enzymes involved in this pathway, including pyruvate carboxylase. This is because insulin promotes glucose uptake and storage, while gluconeogenesis is a mechanism for glucose production. In contrast, insulin increases the activity of enzymes involved in glycolysis, glycogen synthesis, and fatty acid synthesis.

**Why Each Wrong Option is Incorrect**
**Option A:** Glucokinase is an enzyme that phosphorylates glucose to glucose-6-phosphate in the liver, promoting glycolysis. Insulin stimulates the activity of glucokinase, making this option incorrect.

**Option C:** Glycogen synthase is an enzyme that catalyzes the synthesis of glycogen from glucose-1-phosphate. Insulin activates glycogen synthase, promoting glycogen storage in the liver and muscles.

**Option D:** Acetyl-CoA carboxylase is an enzyme involved in the synthesis of fatty acids from acetyl-CoA. Insulin stimulates the activity of acetyl-CoA carboxylase, promoting fatty acid synthesis.

**Clinical Pearl / High-Yield Fact**
Insulin's effects on glucose metabolism are crucial for maintaining normal blood glucose levels. Understanding the regulation of enzymes involved in glycolysis, glycogen synthesis, and fatty acid synthesis is essential for managing diabetes and other metabolic disorders.

**✓ Correct Answer: B. Pyruvate carboxylase**