24. The immediate, direct effect of auxin in cell elongation, according to the acid growth hypothesis, is to
(A) increase the hydrostatic pressure in cells, stretching their walls.
(B) activate ATP-driven proton (W) pumps, and result in an accumulation ofW in cytoplasm.
(C) shift the pH and thus activate enzymes that break the hydrogen bonds.
(D) move water into vacuoles.
(E) activate the synthesis of new cytoplasm.