**Core Concept**
Hepatic glycogen is the primary storage form of glucose in the liver, playing a crucial role in maintaining blood glucose levels, especially during fasting or starvation. The liver can store glycogen in the form of alpha-1,4-glycosidic bonds, which can be broken down into glucose for energy production.

**Why the Correct Answer is Right**
During starvation, the body initially relies on stored glycogen for energy. However, the liver's glycogen stores are limited and can be depleted within a short period. This depletion occurs due to the breakdown of glycogen to glucose through the action of glycogen phosphorylase, an enzyme that catalyzes the phosphorolysis of alpha-1,4-glycosidic bonds in glycogen. The breakdown of glycogen to glucose is a rapid process, and the liver's glycogen stores can be depleted within 12-18 hours of starvation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the liver's glycogen stores are depleted within a shorter time frame than 24-48 hours.
**Option B:** This option is incorrect because the liver's glycogen stores are depleted due to the breakdown of glycogen to glucose, not due to the conversion of glucose to glycogen.
**Option C:** This option is incorrect because the liver's glycogen stores are depleted within a shorter time frame than 48-72 hours.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the liver's glycogen stores are limited and can be depleted within 12-18 hours of starvation, highlighting the importance of gluconeogenesis and the breakdown of fat and protein for energy production during prolonged fasting.

**Correct Answer:** A. 12-18 hours