**Core Concept**
Glucose homeostasis is tightly regulated through various mechanisms, including glycogen storage and release in the liver. The enzyme defect in question affects this process, leading to hypoglycemia, particularly in the fasting state.

**Why the Correct Answer is Right**
The scenario describes a condition where glucagon, a hormone that typically raises blood glucose by stimulating glycogen breakdown, is ineffective during fasting but effective after meals. This suggests an issue with glycogenolysis, the process by which glycogen is broken down to glucose. The liver biopsy showing increased glycogen deposits further supports this theory, as glycogen is being stored but not being released. This is consistent with a deficiency in the enzyme glycogen phosphorylase, which is responsible for breaking down glycogen to glucose-1-phosphate.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided. Please provide the complete question with all options.

**Clinical Pearl / High-Yield Fact**
The key point to remember is that glycogen storage diseases often present with hypoglycemia, particularly in the fasting state, and may be associated with increased glycogen deposits in the liver. The effectiveness of glucagon in raising blood glucose can be a useful clue in diagnosing these conditions.

**Correct Answer:** C. Glycogen phosphorylase deficiency (GSD Type VI, Hers' disease)