Okay, let's tackle this question about Wolman's Disease. The question is asking which cell organelle is affected. First, I need to recall what Wolman's Disease is. I remember it's a lysosomal storage disorder. Lysosomes are the organelles involved in breaking down various biomolecules.

Wolman's Disease is caused by a deficiency in the enzyme acid lipase (also known as lysosomal lipase). This enzyme is crucial for breaking down cholesterol esters and triglycerides. Without it, these lipids accumulate in lysosomes, leading to their dysfunction. The lysosomes become engorged with undigested material, which impairs their ability to function properly. This leads to the clinical manifestations of the disease, such as hepatosplenomegaly and adrenal calcifications.

Now, looking at the options, the correct answer should be the lysosome. The other options might include other organelles like mitochondria, endoplasmic reticulum, or peroxisomes. Let's think: Mitochondrial diseases are usually related to energy production, not lipid storage. Peroxisomal disorders involve enzymes like catalase or peroxidases. The endoplasmic reticulum is more involved in protein synthesis and lipid metabolism, but not storage. So, the lysosome is the key here.

Clinical pearl: Remember that lysosomal storage diseases are grouped by the specific enzyme deficiency. Wolman's is due to acid lipase deficiency, leading to cholesteryl ester accumulation. Another example is Gaucher's disease, which is due to glucocerebrosidase deficiency affecting glucocerebrosides.

So the correct answer is lysosome. The question is testing knowledge of lysosomal storage diseases and their associated enzymes and organelles.

**Core Concept**
Wolman’s Disease is a **lysosomal storage disorder** caused by **acid lipase (lysosomal lipase) deficiency**, leading to **cholesteryl ester and triglyceride accumulation** within lysosomes. The **lysosome** is the primary organelle affected due to its role in lipid metabolism and degradation.

**Why the Correct Answer is Right**
Acid lipase deficiency impairs lysosomal breakdown of **cholesteryl esters and triglycerides**, causing their toxic accumulation in lysosomes. This leads to **lysosomal dysfunction**, **hepatosplenomegaly**, **adrenal calcifications**, and **systemic inflammation**. The disease is **autosomal recessive** and presents in infancy with severe, often fatal outcomes if untreated.

**Why Each Wrong Option is Incorrect**
**Option A:** Mitochondria are involved in energy production, not lipid storage.
**Option B:** Endoplasmic reticulum (ER) is responsible for protein/lipid synthesis, not degradation.
**Option C:** Peroxisomes break down very long-chain fatty acids but are not central to Wolman’s pathophysiology.

**Clinical Pearl / High-Yield Fact**
Remember **lysosomal storage diseases** by their **key enzymes and substrates**:
- **Wolman’s**: Acid lipase → Cholesteryl esters/triglycerides.
- **Gaucher’s**: Glucocerebrosidase → Glucocerebrosides.
Differentiate from **Tay-Sachs** (lysosomal enzyme:

✓ Correct Answer: B. Lysosome