**Core Concept**
In starvation, the body undergoes a catabolic state, breaking down muscle tissue to provide essential amino acids for gluconeogenesis and reducing muscle mass. This process involves the transport of nitrogen from muscle to liver and kidney for excretion and gluconeogenesis.

**Why the Correct Answer is Right**
The correct answer involves the transport of amino acids from muscle to liver and kidney via the bloodstream. During starvation, muscle tissue breaks down to release amino acids, which are then deaminated by the enzyme alanine aminotransferase (ALT) in muscle cells. The resulting alpha-keto acid is converted to pyruvate, which is then transported to the liver via the bloodstream. In the liver, pyruvate is converted to glucose via gluconeogenesis. Simultaneously, the ammonia group from the deamination reaction is transported to the liver and kidney via the bloodstream, where it is converted to urea and excreted. The key enzyme involved in this process is alanine aminotransferase (ALT), which catalyzes the transfer of an amino group from alanine to alpha-ketoglutarate.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the correct mechanism of nitrogen transport from muscle to liver and kidney.
* **Option B:** This option is incorrect because it does not accurately describe the role of the bloodstream in transporting amino acids and ammonia during starvation.
* **Option C:** This option is incorrect because it does not identify the key enzyme (alanine aminotransferase) involved in the deamination reaction.

**Clinical Pearl / High-Yield Fact**
The process of nitrogen transport from muscle to liver and kidney during starvation is a critical adaptation that allows the body to conserve glucose and maintain energy homeostasis. This process is mediated by the enzyme alanine aminotransferase (ALT), which plays a key role in the deamination reaction.

**Correct Answer:** C. Alanine.