Ans. Glycogen.
The glucose is primary fuel for the all body activities, but it acts as short term energy storage compound. The glucose is converted into long-term energy storage compound, glycogen. This process is known as glycogenesis and occurs in liver cells mainly.
The glycogen is stored in liver cells and skeletal muscle cells, which is converted into glucose for energy production, when required.
Thus, the correct answer is 'glycogen.'
