Solve this:
Q.144. During creation of proton gradient in chloroplast, protons are removed from the :-
(1) Stroma by ATP synthase
(2) Stroma by NADP reductase enzyme
(3) Thylakoid lumen by NADP reductase enzyme
(4) Thylakoid Lumen by cytochrome b & f

Dear Student, 

During  generation of a proton gradient in chloroplasts:
 

1. water is oxidized and the protons are released
2. Proton is pumped into the thylakoid lumen by cytrochrome bf complex.
3. Protons removed from the stroma by the reduction of NADP and plastoquinone.  The enzyme NADP reductase is located on stroma side of membrane alongwith electrons coming from PSI. Protons are also needed to reduce NADP+  to  NADPH. Hence, these protons are removed from stroma.