What is the primary role of chlorophyll in plants?

Chlorophyll plays a crucial role in photosynthesis, which is the process by which plants convert light energy, typically from the sun, into chemical energy stored in glucose. Chlorophyll is the green pigment found in the chloroplasts of plant cells, and it absorbs light most efficiently in the blue and red wavelengths while reflecting green light, which is why plants appear green.

During photosynthesis, chlorophyll facilitates the conversion of carbon dioxide and water into glucose and oxygen, using the absorbed light energy. This process is vital for the plant's growth and energy production, as it provides the necessary sugars that serve as fuel for various metabolic processes within the plant. Ultimately, photosynthesis supports the entire ecosystem by supplying oxygen and serving as the foundation of the food web, as plants are primary producers.

The other choices do not accurately represent the main function of chlorophyll. Water retention relates to processes like transpiration; protection from pests might involve different chemical compounds or structures rather than chlorophyll; and transpiration is a mechanism by which plants regulate water loss, which is separate from the role chlorophyll plays in energy conversion.