**Core Concept**
During starvation, the body undergoes a series of adaptations to maintain energy homeostasis. This involves the catabolism of stored fats, proteins, and carbohydrates to produce energy. Several key enzymes play a crucial role in these metabolic processes, and their activities are modulated accordingly.

**Why the Correct Answer is Right**
The correct answer involves identifying the enzyme whose activity does not increase during starvation. This is a critical aspect of understanding the metabolic adaptations that occur in the body when it is deprived of exogenous glucose.

* **Option A:** Phosphoenolpyruvate carboxykinase (PEPCK) - This enzyme is involved in gluconeogenesis, the process by which the body generates glucose from non-carbohydrate sources. During starvation, PEPCK activity increases to facilitate gluconeogenesis and maintain blood glucose levels.
* **Option B:** Pyruvate dehydrogenase (PDH) - This enzyme is a key regulator of the transition from glycolysis to the citric acid cycle. However, during starvation, the activity of PDH actually decreases due to the lack of NAD+ and the presence of high levels of acetyl-CoA, which inhibits the enzyme.
* **Option C:** Glucagon - This hormone is released by the pancreas in response to low blood glucose levels and stimulates gluconeogenesis and glycogenolysis. During starvation, glucagon levels are elevated, and its activity increases to facilitate the breakdown of stored glycogen and the generation of glucose.
* **Option D:** Carnitine palmitoyltransferase 1 (CPT1) - This enzyme is involved in the transport of long-chain fatty acids into the mitochondria for beta-oxidation. During starvation, CPT1 activity increases to facilitate the breakdown of stored fats and the production of ketone bodies.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that PDH activity decreases during starvation due to the lack of NAD+ and the presence of high levels of acetyl-CoA. This is a critical adaptation that allows the body to prioritize the breakdown of fats and the production of ketone bodies over the oxidation of pyruvate.

**Correct Answer:** B. Pyruvate dehydrogenase (PDH)