What condition is required for atp synthase to move hydrogen down its gradient?

a. more hydrogen ions inside the membrane than outside it
b. more hydrogen ions outside the membrane than inside it
c. a day with 75 percent direct sunlight
d. more atp molecules ahead of the hydrogen than below it

A. More hydrogen ions inside the membrane than outside it

Explanation:

During electron transfer from water molecule to PS II and then through electron transport chain to the PS I pumps the hydrogen ions inside the thylakoid lumen. ATP synthesis is driven by energy of proton concentration gradient that moves the hydrogen ions (protons) from lumen of thylakoid membrane towards the stroma. Hence, ATP synthesis requires presence of more hydrogen ions inside the membrane.

i won't lie i don't know so go online and ask google thats what i do