**Core Concept**
Oxidative deamination is a process in which an amino group is removed from an amino acid, resulting in the production of a keto acid and ammonia. This process is an important step in the catabolism of amino acids and is catalyzed by specific enzymes.

**Why the Correct Answer is Right**
Glutamate dehydrogenase is a key enzyme involved in oxidative deamination. It catalyzes the conversion of glutamate to α-ketoglutarate, releasing ammonia in the process. This reaction is reversible, allowing glutamate to be synthesized from α-ketoglutarate in the presence of ammonia. Glutamate dehydrogenase is a mitochondrial enzyme that plays a crucial role in the regulation of glutamate and α-ketoglutarate levels in the cell.

**Why Each Wrong Option is Incorrect**
**Option A:** Glutaminase is an enzyme that catalyzes the hydrolysis of glutamine to glutamate and ammonia, but it is not involved in oxidative deamination.

**Option B:** Glutamine synthase is an enzyme that catalyzes the condensation of glutamate and ammonia to form glutamine, which is the opposite of oxidative deamination.

**Option D:** None of the above is incorrect because glutamate dehydrogenase is indeed the correct answer.

**Clinical Pearl / High-Yield Fact**
It's worth noting that oxidative deamination is an important mechanism by which the body regulates glutamate levels, particularly in the brain. Imbalances in glutamate and glutamine metabolism have been implicated in various neurological disorders, including epilepsy and schizophrenia.

**✓ Correct Answer: C. Glutamate dehydrogenase**