## Core Concept
Fabry's disease is a genetic disorder that falls under the category of lysosomal storage diseases. It is caused by the deficiency of a specific enzyme involved in the breakdown of certain lipids. This deficiency leads to the accumulation of these lipids within cells, resulting in various clinical manifestations.

## Why the Correct Answer is Right
The correct answer, **C. Alpha-Gal A (Alpha-Galactosidase A)**, is right because Fabry's disease is indeed caused by a deficiency of alpha-Gal A, also known as alpha-Galactosidase A. This enzyme is crucial for the breakdown of globotriaosylceramide (Gb3 or GL-3), a type of lipid. Without sufficient alpha-Gal A, Gb3 accumulates within the lysosomes of cells, leading to cellular dysfunction and the clinical features of Fabry's disease, which include pain, neuropathy, and renal and cardiac complications.

## Why Each Wrong Option is Incorrect
- **Option A: Acid Lipase** - This enzyme is related to a different lysosomal storage disease known as Wolman's disease and cholesteryl ester storage disease, not Fabry's disease.
- **Option B: Glucocerebrosidase** - This enzyme is associated with Gaucher's disease, another type of lysosomal storage disease, and is not related to Fabry's disease.
- **Option D: Sphingomyelinase** - This enzyme is deficient in Niemann-Pick disease, a group of lysosomal storage diseases, and is not related to Fabry's disease.

## Clinical Pearl / High-Yield Fact
A key clinical pearl for Fabry's disease is that it is an X-linked disorder, meaning it predominantly affects males, who have one X chromosome. Females can be carriers or, less commonly, be affected if they are homozygous for the mutation. A classic clinical feature is the presence of angiokeratomas, which are small, non-blanching vascular spots on the skin.

## Correct Answer: C. Alpha-Gal A (Alpha-Galactosidase A)