Here's why:

* Chloroplasts are organelles found in plant cells and some algae. They are the sites of photosynthesis, the process by which plants convert light energy into chemical energy.

* Pigments like chlorophyll (which gives plants their green color) are embedded within the chloroplast's internal membranes. These pigments absorb light energy, primarily from the red and blue wavelengths of the visible spectrum.

* This absorbed light energy is then used to power the chemical reactions that convert carbon dioxide and water into glucose (sugar) and oxygen.

So, chloroplasts are the structures that house the pigments responsible for capturing light energy in photosynthesis.