Answer: water
The light reactions of noncyclic photophosphorylation takes place in the chloroplast. The light energy is converted to chemical energy to produce both ATP and NADPH, which act as energy-transfer molecules in the light-independent reactions of the Calvin cycle. The addition of phosphate due to synthesizing of ATP by cells results to photophosphorylation.
Moreover, the electrons from water replenish chlorophyll molecules that have given up electrons by photolysis. The two electrons from the water molecule are kept in photosystem II, while the 2H+ and 1/2O2 are left out for further use.
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