**Core Concept**
Galactosemia is a congenital disorder characterized by the inability to properly metabolize galactose, a sugar found in milk and other dairy products. This metabolic disorder affects the conversion of galactose to glucose, leading to its accumulation in the body.

**Why the Correct Answer is Right**
The correct answer is related to the enzyme galactose-1-phosphate uridyltransferase (GALT), which is crucial in the Leloir pathway for converting galactose to glucose. A deficiency in GALT leads to the accumulation of galactose-1-phosphate, causing damage to the liver, kidneys, and brain. The enzyme catalyzes the transfer of a uridyl group from UDP-glucose to galactose-1-phosphate, forming UDP-galactose and glucose-1-phosphate.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the enzyme responsible for galactose metabolism.
* **Option B:** This option is incorrect because it refers to a different enzyme, not directly involved in galactose metabolism.
* **Option D:** This option is incorrect because it is not a relevant enzyme in the context of galactose metabolism.

**Clinical Pearl / High-Yield Fact**
Galactosemia can be treated with a strict galactose-free diet, which is essential for preventing the accumulation of toxic metabolites and preventing long-term complications.

**Correct Answer: C. Galactose-1-phosphate uridyltransferase (GALT)**