**Core Concept**
During starvation, the body undergoes a series of metabolic changes to adapt to the lack of glucose as a primary energy source. The liver plays a crucial role in these adaptations by altering the expression and activity of various enzymes involved in glucose, lipid, and protein metabolism.

**Why the Correct Answer is Right**
During starvation, the body begins to break down stored fat for energy. Fatty acid synthase is a key enzyme responsible for the synthesis of fatty acids from acetyl-CoA and malonyl-CoA in the cytoplasm of adipocytes. However, when the body is in a fasting state, the demand for fatty acid synthesis decreases, and the expression of fatty acid synthase is downregulated. This allows the body to increase the breakdown of fatty acids for energy. In contrast, CoA carnitine transferase (also known as carnitine palmitoyltransferase) is involved in the transport of long-chain fatty acids into the mitochondria for beta-oxidation, which is actually increased during starvation.

**Why Each Wrong Option is Incorrect**
* **Option B:** CoA carnitine transferase is actually increased during starvation to facilitate the breakdown of fatty acids for energy.
* **Option C:** Citrate lyase is an enzyme involved in the breakdown of citrate to acetyl-CoA, which is increased during starvation to provide energy for the brain and other tissues.
* **Option D:** Lipoprotein lipase is an enzyme involved in the breakdown of triglycerides in lipoproteins, which is also increased during starvation to provide fatty acids for energy.
* **Option E:** Tyrosine kinase is an enzyme involved in the signaling pathways of various hormones and growth factors, which is not directly related to the metabolic changes that occur during starvation.

**Clinical Pearl / High-Yield Fact**
During prolonged fasting or starvation, the body's ability to synthesize fatty acids is decreased, and the breakdown of stored fat is increased. This is due to the downregulation of fatty acid synthase and the upregulation of enzymes involved in fatty acid breakdown, such as CoA carnitine transferase.

**Correct Answer:** A. Fatty acid synthase.