Answer
C.
Work Step by Step
Active transport builds up a gradient by expending energy, which gradient can then be used to drive other, coupled transport (C.). ATP is not used directly by coupled transport, and not always by active transport, falsifying A., and B. is untrue because coupled transport does make a gradient, exchanging the one established by active transport for another one. D. is eliminated since this could be true in some cases, but there is no universal relationship like the one stated.
