Here's why:

* Photosynthesis: Chloroplasts are the sites of photosynthesis, the process by which plants and some other organisms use sunlight, water, and carbon dioxide to create glucose (a type of sugar) and oxygen.

* Chlorophyll: Chloroplasts contain chlorophyll, a green pigment that absorbs light energy, particularly in the red and blue wavelengths.

* Energy Conversion: The absorbed light energy is used to convert carbon dioxide and water into glucose, storing the energy from sunlight in the chemical bonds of the sugar molecule.

So, chloroplasts are the powerhouse of plant cells when it comes to using sunlight to create food.