* Photosynthesis and Light: Plants use light energy to fuel photosynthesis, the process of converting light energy into chemical energy (sugars). Different wavelengths of light are absorbed differently by chlorophyll, the pigment responsible for photosynthesis.

* Red Light's Role: Red light is most effectively absorbed by chlorophyll. This means plants can use red light very efficiently to create energy for growth.

* Green Light's Role: Green light is actually reflected by chlorophyll. While some green light is still used, it's less efficient than red light.

In short, the plant exposed to red light will have more energy available for growth and will therefore thrive better.