The answer is b. it is a product formed. Photosynthesis is being done with the use of light, carbon dioxide and the water. This then will have an end product which is glucose which then can be use as a food source. Hope this answer would be of help.
Glucose is the product that is formed along with oxygen (which then excreted by plants as waste product; the same oxygen that we breathe) in photosynthesis. Photosynthesis is the ability of plants to synthesize glucose from inorganic matter which are carbon dioxide and oxygen using sunlight as a catalyst hence the name "photo" means light and "synthesis" which means to combine.
