**Core Concept**
Gluconeogenesis is a metabolic pathway that generates glucose from non-carbohydrate sources, such as amino acids, lactate, and glycerol. This process is crucial for maintaining blood glucose levels, especially during fasting or starvation states. The hormone that stimulates gluconeogenesis is a key regulator of this pathway.

**Why the Correct Answer is Right**
Glucagon is a hormone secreted by the pancreas in response to low blood glucose levels. It stimulates gluconeogenesis by activating key enzymes involved in this pathway, such as phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-bisphosphatase. Glucagon also promotes the breakdown of glycogen stored in the liver and muscle tissues to release glucose into the bloodstream. This hormonal response is essential for maintaining blood glucose homeostasis during periods of fasting or low glucose availability.

**Why Each Wrong Option is Incorrect**
**Option A:** Insulin - Insulin is a hormone that inhibits gluconeogenesis by promoting the storage of glucose in the form of glycogen and suppressing the expression of key gluconeogenic enzymes.

**Option B:** Adrenaline (Epinephrine) - Adrenaline stimulates glycogenolysis and lipolysis, but it does not directly stimulate gluconeogenesis.

**Option C:** Thyroid-stimulating hormone (TSH) - TSH is a hormone that regulates thyroid function, but it does not have a direct role in stimulating gluconeogenesis.

**Clinical Pearl / High-Yield Fact**
Glucagon is often used clinically to diagnose and treat hypoglycemia, particularly in patients with diabetes. It is also used as an antidote for insulin overdose.

**Correct Answer:** C. Glucagon stimulates gluconeogenesis by activating key enzymes and promoting glycogen breakdown.