Correct Option: A

Photosynthesis, process by which green plants and certain other organisms use the energy of light to convert carbon dioxide and water into the simple sugar glucose. The wavelength most effective in conducting photosynthesis is 420nm. Actually, 420nm is on the blue side of the spectrum, which makes up between 1 and 10% of the light needed for photosynthesis. There is a plateau on the blue side when comparing blue wavelength effects on photosynthesis, and 420nm is right on the edge of it. 430nm would be more in the middle of the plateau, making it the safer bet. Plants need red light, and lots of it. Red light contributes to over 90% of photosynthesis.