Answer:
From Hydrogen ion.
H+
Explanation:
It's is from hydrogen ion because majoroty of the electrons transport processes take place in the thylakoids membranes in a bid to produced ATP, Hydrogen ion is allow to move through thylakoid space and then backflow through the proteins embedded in the thylakoids membrane called ATP synthase, which produce ATP from ADP in the mitochondrial matrix and chloroplast stroma.
The Answer Is A. Hope This Helps ;P
Carbon dioxide is the compound in photosynthesis, I'm pretty sure
