In an experiment, isolated chloroplast thylakoids were incubated at pH 4.0 with ADP and inorganic phosphate (Pi) added to the medium and then transferred to a medium having pH 8.0. After sometime, an agent 'X' that makes membrane permeable to protons is added to it. What would occur?
A. On transferring to medium with pH 8.0, ATP formation would happen only on addition of X.
B. There will be ATP formation in the medium at pH 8.0 and X will have no effect.
C. At pH 8.0, ATP would be produced, but if X is added, ATP formation will stop.
D. There will be ATP formation in the medium at pH 8.0 and addition of X will increase it.