The correct answer is B. water.
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms’ activities. This chemical energy is stored in molecules of the sugar glucose.
The process of photosynthesis takes place in two stages: the light-dependent reactions and the Calvin cycle.
The light-dependent reactions take place in the thylakoid membrane of chloroplasts. During these reactions, light energy is used to split water molecules into hydrogen ions and oxygen gas. The hydrogen ions are then used to produce ATP, a molecule that stores energy. The oxygen gas is released into the atmosphere.
The Calvin cycle takes place in the stroma of chloroplasts. During this cycle, carbon dioxide is used to produce glucose. The ATP and NADPH produced during the light-dependent reactions are used to power the Calvin cycle.
The overall reaction for photosynthesis is:
6CO2 + 6H2O + light energy â C6H12O6 + 6O2
As you can see from the equation, the oxygen gas released during photosynthesis comes from water.