Answer:
Nutrition.
Explanation:
Photosynthesis is a process in which plants, some algae and cyanobacteria create food and oxygen out of carbon dioxide and sunlight.
Therefore, the main role of photosynthesis is to provide food for the plant, since producing oxygen isn't exactly beneficial for the plant; it is a secondary product of the process and part of an "ecosystemic cycle".
Hope it helped,
BiologiaMagister
