The correct answer is option 3 - Glycogen. Glucose is the primary source of energy for our body, but it is not stored as glucose itself. Instead, it is stored in the form of glycogen. Glycogen is a large, branched chain of glucose molecules linked together. It is mainly stored in the liver and muscles. When glucose levels in the blood are high, insulin signals the liver and muscles to convert excess glucose into glycogen for storage. Then, when blood glucose levels drop, the stored glycogen is broken down into glucose and released back into the bloodstream to maintain a steady supply of energy. Insulin, mentioned in option 1, is a hormone that regulates glucose levels in the blood and helps in the storage and utilization of glucose, but it is not the storage form itself. So, the correct answer is glycogen.