The correct answer would be b. the products of cellular respiration are the same as the reactants of photosynthesis. Here are the equations for each:
Photosynthesis:
6CO2 + 6H2O + sunlight --> C6H12O6 + 6O2
OR
6 carbon dioxide + 6 water + sunlight --> glucose + 6 oxygen
Cellular respiration:
C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP
OR
glucose + 6 oxygen --> 6 carbon dioxide + 6 water + energy
Notice how the products and reactants are switched? The only difference is that photosynthesis requires sunlight, while cellular respiration produces ATP. Hope this helped! :)