**Core Concept**
The transfer of an amino group from an amino acid to an alpha-keto acid is a crucial step in amino acid metabolism. This process is facilitated by specific enzymes that catalyze the conversion of alpha-keto acids to amino acids, a process known as transamination.

**Why the Correct Answer is Right**
Transamination involves the transfer of an amino group (-NH2) from an amino acid to an alpha-keto acid, resulting in the formation of a new amino acid and a corresponding keto acid. This reaction is catalyzed by transaminases, also known as aminotransferases. These enzymes require pyridoxal phosphate (PLP), a derivative of vitamin B6, as a cofactor to facilitate the transfer of the amino group. The correct answer is the enzyme responsible for catalyzing this reaction.

**Why Each Wrong Option is Incorrect**
* **Option A:** is incorrect because it is a different enzyme involved in a distinct biochemical pathway.
* **Option B:** is incorrect because it is a type of enzyme involved in a different metabolic process.
* **Option D:** is incorrect because it is not directly involved in transamination reactions.

**Clinical Pearl / High-Yield Fact**
Transamination reactions are essential for the synthesis and degradation of amino acids in the body. These reactions allow for the recycling of nitrogen and the conversion of one amino acid into another, which is crucial for maintaining nitrogen balance and supporting protein synthesis.

**Correct Answer:** C. Aminotransferase.