**Core Concept**
When glucose 6-phosphate (G6P) is present in the fed state, the primary fate of this molecule in tissues is to be stored as glycogen, a complex carbohydrate that serves as a readily mobilizable energy reserve. This process involves the enzyme glycogen synthase, which catalyzes the transfer of glucose units from UDP-glucose to the growing glycogen chain.

**Why the Correct Answer is Right**
In the fed state, the concentration of glucose 6-phosphate is high due to the presence of glucose in the bloodstream. The enzyme glycogen synthase is activated by insulin, which promotes the storage of glucose as glycogen in the liver and muscles. This process is essential for maintaining blood glucose levels within a narrow range and providing a readily mobilizable energy reserve. The enzyme glycogen synthase catalyzes the transfer of glucose units from UDP-glucose to the growing glycogen chain, resulting in the storage of glucose 6-phosphate as glycogen.

**Why Each Wrong Option is Incorrect**
**Option A:** Storage as Fructose - This option is incorrect because fructose is a different sugar molecule that is not directly related to the storage of glucose 6-phosphate. Fructose is metabolized through a separate pathway that involves the enzyme aldolase B.

**Option B:** Storage as Glyceraldehyde 3-PO4 - This option is incorrect because glyceraldehyde 3-phosphate is an intermediate in the glycolytic pathway, not a storage form of glucose 6-phosphate. Glyceraldehyde 3-phosphate is a key molecule in the metabolism of glucose, but it is not stored in tissues.

**Option C:** Enters HMP shunt Ribulose 5-PO4 - This option is incorrect because the hexose monophosphate (HMP) shunt, also known as the pentose phosphate pathway, is a metabolic pathway that generates NADPH and pentoses from glucose 6-phosphate. However, ribulose 5-phosphate is an intermediate in this pathway, not a storage form of glucose 6-phosphate.

**Clinical Pearl / High-Yield Fact**
In the fasting state, the enzyme glycogen phosphorylase is activated, breaking down glycogen to glucose 6-phosphate, which is then released into the bloodstream to maintain blood glucose levels. This process is essential for maintaining glucose homeostasis.

**✓ Correct Answer: D. Storage as glycogen**