Which sunlight/Sunrays used by green plants to make their food by process of photosynthesis?
You can read about absorption of Sunlight during Photosynthesis at the following link, This requires a big explanation with diagrams so please follow the link to understand the concept properly.
https://www.khanacademy.org/science/biology/photosynthesis-in-plants/the-light-dependent-reactions-of-photosynthesis/a/light-and-photosynthetic-pigments