**Core Concept**
Gaucher's disease is a genetic disorder characterized by the deficiency of a lysosomal enzyme, leading to the accumulation of sphingolipids, particularly glucocerebroside, in various tissues. This accumulation causes cellular dysfunction and tissue damage, resulting in a range of clinical manifestations.

**Why the Correct Answer is Right**
The correct answer is glucocerebrosidase, which is the enzyme responsible for breaking down glucocerebroside into glucose and ceramide. In Gaucher's disease, the deficiency of glucocerebrosidase leads to the accumulation of glucocerebroside in lysosomes, causing cellular dysfunction and tissue damage. This enzyme deficiency is due to mutations in the GBA gene, which codes for the glucocerebrosidase enzyme.

**Why Each Wrong Option is Incorrect**
* **Option A:** Acid beta-glucosidase is the correct enzyme name for glucocerebrosidase.
* **Option B:** Galactocerebrosidase is a different enzyme involved in the breakdown of galactocerebroside.
* **Option C:** Sphingomyelinase is an enzyme involved in the breakdown of sphingomyelin, which is a different sphingolipid.

**Clinical Pearl / High-Yield Fact**
Gaucher's disease is an autosomal recessive disorder, meaning that an individual must inherit two defective copies of the GBA gene (one from each parent) to develop the disease. This is an important consideration for genetic counseling and family planning.

**Correct Answer: A. Acid beta-glucosidase.