The correct option is D Glycogen
Glucose is stored in the form of glycogen in animals. The two main site of storage of glycogen is liver and muscles. The excess glucose is linked together as a multibranched polysaccharide to serve for long term energy reserve, Muscle glycogen is kept as an immediate resource of energy as and when required. As during exercising muscle glycogen is broken to glucose which via glycolysis produces energy for the exercise. Liver glycogen is kept for emergency reserve in cases of starving, to provide glucose to vital organs like brain. So, the correct answer is 'Glycogen'.