**Core Concept**
The question is testing the understanding of a specific reaction of acetaldehyde, a toxic metabolite of alcohol, which is responsible for the adverse effects of alcohol consumption, particularly in certain populations.

**Why the Correct Answer is Right**
Acetaldehyde is the primary metabolite of ethanol, formed by the action of alcohol dehydrogenase (ADH) in the liver. In individuals of East Asian and Native American descent, a genetic variant of ADH (ADH2*2) is more prevalent, leading to increased production of acetaldehyde. The subsequent accumulation of acetaldehyde causes a range of symptoms, including facial flushing, nausea, and rapid heartbeat. The flushing reaction is due to the direct vasodilatory effect of acetaldehyde on blood vessels.

**Why Each Wrong Option is Incorrect**
**Option A:** Acetone is a ketone body produced during ketosis, which is not directly related to the flushing reaction in Asian populations.
**Option B:** Ethanol itself does not cause flushing; rather, it is metabolized to acetaldehyde, which is responsible for the symptoms.
**Option C:** Fatty acid metabolites are not directly involved in the flushing reaction associated with acetaldehyde accumulation.

**Clinical Pearl / High-Yield Fact**
It is essential to recognize that individuals with a history of facial flushing after consuming alcohol may be at increased risk of developing alcohol use disorders due to the unpleasant symptoms associated with acetaldehyde accumulation.

**Correct Answer: C. Acetaldehyde**