Answer:
Option D, Hydrogen ions flow down a concentration gradient from the thylakoid space to the stroma through ATP synthase, releasing energy that can be used to produce ATP from ADP + Pi.
Explanation:
The hydrogen ion released during the breaking of water molecule starts building in the thylakoid space. This causes a difference in concentration across the membrane due to difference in build proton concentration and the charges created across the membrane.
Potential energy obtained from this set up is collected and stored as chemical energy in ATP through the assistance of enzyme ATP synthase
Option D is correct