Here's why:

* Glycogen is a complex carbohydrate made up of many glucose molecules linked together. It's found primarily in the liver and muscles. When your body needs energy, glycogen is broken down into glucose for use.

Let's look at the other options:

* Glucose itself is the simple sugar that provides energy. It's not the storage form.

* Starch is a complex carbohydrate found in plants, not humans. It's similar to glycogen in structure but is not our primary glucose storage form.

* Sucrose is a simple sugar (table sugar) made of glucose and fructose. It's not stored in the body as is.

Let me know if you have any other questions!