Explanation:

- Option 1: Glycogen

- Correct Answer: Glycogen is often referred to as "animal starch" because it serves as the primary form of energy storage in animals, similar to how starch functions in plants.

- It is a highly branched polysaccharide stored in the liver and muscles.

- Option 2: Cellulose

- A structural polysaccharide found in the cell walls of plants.

- It is not used for energy storage in animals.

- Option 3: Glucose

- A simple sugar and the primary energy source for cells.

- It is a monosaccharide used in cellular respiration, not a polysaccharide like glycogen.

- Option 4: Chitin

- A structural polysaccharide found in the exoskeletons of arthropods and cell walls of fungi.

- It does not function as an energy storage molecule in animals.

Correct Answer: Glycogen