Glycogen is the body gets stored mainly in two places which are muscles and liver. During intense exercise glycogen which is stored in the muscle provides the main source of energy. So during exercise blood glucose levels do not reduce much because muscle also uses stored glycogen to get energy so as a result blood glucose level remains stable.
After the exercise, the glycogen in the muscle is again replenished because of the increase rate of glycogen synthesis after the exercise. Therefore the correct answer is muscle.
