Photosynthesis is the name given to the set of chemical reactions performed by plants to convert energy from the sun into chemical energy in the form of sugar. Specifically, plants use energy from sunlight to react carbon dioxide and water to produce sugar (glucose) and oxygen. Many reactions occur, but the overall chemical reaction for photosynthesis is:
6 CO2 + 6 H2O + light → C6H12O6 + 6 O2
So it would be C, I hope this helped! :)