**Question:** In maple syrup urine disease, the FeCl3 test with urine gives a ____ color.

**Core Concept:** Maple syrup urine disease (MSUD) is a rare, inherited disorder that affects the way the body breaks down certain amino acids. The FeCl3 test is a diagnostic test used to detect the presence of branched-chain α-keto acids in urine, which are elevated in MSUD.

**Why the Correct Answer is Right:** In MSUD, branched-chain α-keto acids (leucine, isoleucine, and valine) are not properly broken down, leading to their accumulation in the urine. This results in the formation of a distinctive, brown color when the urine is mixed with the FeCl3 reagent.

**Why Each Wrong Option is Incorrect:**

A. The correct answer is not a brown color, making this incorrect.
B. This option does not describe the specific color produced by the FeCl3 test in MSUD.
C. The correct answer is not a yellow color, making this incorrect.
D. This option does not describe the specific color produced by the FeCl3 test in MSUD.

**Clinical Pearl:** The FeCl3 test in MSUD is crucial for diagnosis as it provides a positive result indicating the presence of branched-chain α-keto acids in the urine.

**Correct Answer:** D. Brown (Brown color indicates the presence of branched-chain α-keto acids in the urine, which are elevated in MSUD.)