Final answer:
The best description of the products of photosynthesis is that they are also the starting materials for cellular respiration, which includes glucose and oxygen.
Step-by-step explanation:
The statement that BEST describes the products of the photosynthesis process is: They are also the starting materials of cellular respiration. This is because the products of photosynthesis, glucose and oxygen, are used as reactants in cellular respiration. Cellular respiration is the process in which cells break down glucose to produce ATP, the energy currency of the cell, with the byproducts being water and carbon dioxide.
During photosynthesis in plants, water and carbon dioxide are used as reactants to form glucose and oxygen. The oxygen produced is released into the atmosphere and is vital for the survival of aerobic organisms, which utilize it in their own cellular respiration processes. The glucose produced during photosynthesis is used by plants as an energy source and can be stored as larger carbohydrates like starch.