Concept:Photosynthesis converts light energy into chemical energy and produces glucose as the first stable organic sugar.Explanation:During photosynthesis, CO2 and H2O are used to synthesise glucose.This glucose is the first stable product that can be stored and used by the plant.Starch, fructose, and sucrose are formed later from glucose through different biochemical pathways.Thus, among the given options, glucose is the primary stable product.Answer:C. glucose