in the photosynthesis process carbon dioxide / water / sunlight has the role of raw material & if something is a raw material in a process then that something is required for that process ->  sunlight is required for photosynthesis  green plants are a kind of producer & green plants provide food for themselves / animals / consumers by performing photosynthesis ->  producers provide food for themselves by performing photosynthesis  sunlight is required for photosynthesis & producers provide food for themselves by performing photosynthesis ->  sunlight is required for producers to provide food  sunlight is required for producers to provide food & if something is required by a living thing for a process then increasing that something will increase that living thing's ability to perform that process ->  increasing sunlight will increase a producer's ability to provide food  increasing sunlight will increase a producer's ability to provide food & summer has the most sunlight -> producers provide the most food during summer