**Core Concept**
The kidneys play a crucial role in maintaining acid-base balance by regulating the levels of ammonia in the body. Ammonia is a key player in the excretion of excess hydrogen ions, which helps maintain the pH balance in the body. The production of ammonia in the kidneys is an important mechanism for acid-base homeostasis.

**Why the Correct Answer is Right**
The major source of ammonia in the kidneys is the enzyme **carbamoyl phosphate synthetase I (CPS I)**, which is located in the mitochondria of renal tubular cells. CPS I catalyzes the conversion of ammonia (NH3) and carbon dioxide (CO2) to carbamoyl phosphate, which is then used to synthesize urea. The production of ammonia in the kidneys is also facilitated by the enzyme **glutaminase**, which hydrolyzes glutamine to form glutamate and ammonia. The ammonia produced in the kidneys is then excreted in the urine, helping to maintain acid-base balance in the body.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify the correct enzyme involved in ammonia production in the kidneys.
**Option B:** This option is incorrect as it is not a correct enzyme involved in ammonia production in the kidneys.
**Option C:** This option is incorrect as it is not a correct enzyme involved in ammonia production in the kidneys.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the kidneys play a critical role in maintaining acid-base balance by regulating the levels of ammonia in the body. The production of ammonia in the kidneys is an important mechanism for excreting excess hydrogen ions and maintaining pH balance in the body.

**Correct Answer:** D.