* Mitochondria are the powerhouses of the cell. They are responsible for converting the energy stored in food molecules (like glucose) into a usable form of energy called ATP (adenosine triphosphate). This process is called cellular respiration.

Let's break down why other organelles aren't the primary energy storage:

* Chloroplasts: These organelles are found in plant cells and are responsible for photosynthesis, the process of converting light energy into chemical energy. While they produce energy, they don't directly store the energy from food.

* Nucleus: The nucleus contains the cell's DNA and controls cellular activity. It doesn't store energy.

* Golgi apparatus: This organelle processes and packages proteins and lipids. It doesn't directly store energy from food.

* Lysosomes: Lysosomes are responsible for breaking down waste materials within the cell. They don't store energy.

In summary, mitochondria are the key players in extracting and storing energy from food in a form that the cell can use.