## Core Concept
Cori's disease, also known as debranching enzyme deficiency or glycogen storage disease type III, results from a deficiency in the **debranching enzyme** involved in glycogenolysis. This enzyme is crucial for breaking down glycogen into glucose for energy. The disease affects the body's ability to convert glycogen into glucose due to this enzymatic defect.

## Why the Correct Answer is Right
The correct answer, **debranching enzyme**, is the enzyme deficient in Cori's disease. This enzyme is necessary for the hydrolysis of alpha-1,6-glycosidic bonds in glycogen, which are the branch points in the glycogen molecule. Without sufficient debranching enzyme activity, glycogen cannot be completely broken down into glucose, leading to accumulation of abnormal glycogen (limit dextrin) in cells, particularly affecting the liver, heart, and muscles.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not specify the enzyme related to Cori's disease.
- **Option B:** This option is incorrect as it refers to another enzyme or concept not directly related to the specific enzymatic deficiency seen in Cori's disease.
- **Option D:** This option is incorrect because it refers to an unrelated enzyme or concept.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that Cori's disease (Glycogen Storage Disease Type III) presents with **hypoglycemia**, **hepatomegaly**, and sometimes **cardiomyopathy**. It is inherited in an autosomal recessive pattern. Early diagnosis and management can help mitigate some of the complications.

## Correct Answer: C. debranching enzyme