**Core Concept**
Reye's syndrome is a rare but serious condition that affects the brain and liver, typically occurring in children and teenagers recovering from a viral infection, such as influenza or chickenpox. It is characterized by the presence of encephalopathy and fatty liver degeneration, with the exact pathophysiology still not fully understood.

**Why the Correct Answer is Right**
The key feature of Reye's syndrome is the presence of microvesicular steatosis in the liver, which is a hallmark of this condition. This is due to the accumulation of small droplets of fat within the liver cells, leading to liver dysfunction and encephalopathy. The exact mechanism is thought to involve the inhibition of mitochondrial fatty acid oxidation enzymes, such as carnitine palmitoyltransferase 1 (CPT1), by salicylates or other substances.

**Why Each Wrong Option is Incorrect**
**Option A:** Not mentioned in the context of Reye's syndrome.
**Option B:** This is actually a characteristic of Reye's syndrome, as the liver is affected by microvesicular steatosis.
**Option C:** This is also a feature of Reye's syndrome, as the brain is affected by encephalopathy.

**Clinical Pearl / High-Yield Fact**
Reye's syndrome is often associated with the use of aspirin or other salicylates in children and teenagers recovering from a viral infection, making it essential to avoid these medications in this population.

**Correct Answer: D.**