Where do the protons come from that make up the proton gradient used in the light reactions of photosynthesis?

Where do the protons come from that make up the proton gradient used i

1.	Where do the protons come from that make up the proton gradient used in the light reactions of photosynthesis?
A.	ATP
B.	Glucose
C.	NADPH
D.	H2O
Answer» E.