**Core Concept**
Reye's syndrome is a rare but serious condition that causes swelling in the liver and brain, often triggered by the use of aspirin in children with viral infections. The pathophysiology involves mitochondrial dysfunction and inflammation in the liver.

**Why the Correct Answer is Right**
The correct answer is based on the characteristic histopathological findings in Reye's syndrome. **Option D: Sudan Black B** is the correct answer because Sudan Black B stain is used to identify fatty changes in the liver, which are a hallmark of Reye's syndrome. The liver in Reye's syndrome shows microvesicular steatosis, where there is an accumulation of small fat droplets within the hepatocytes.

**Why Each Wrong Option is Incorrect**
* **Option A:** H&E stain is a general-purpose stain used for histopathological examination, but it is not specific for diagnosing Reye's syndrome.
* **Option B:** Periodic Acid-Schiff (PAS) stain is used to detect glycogen and other carbohydrates in tissues, but it is not used for diagnosing Reye's syndrome.
* **Option C:** Alcian blue stain is used to detect mucopolysaccharides and glycoproteins in tissues, but it is not used for diagnosing Reye's syndrome.

**Clinical Pearl / High-Yield Fact**
Reye's syndrome is a rare but serious condition that can be prevented by avoiding the use of aspirin in children with viral infections.

**Correct Answer: D. Sudan Black B**