Final answer:
If molecules are pumped across a membrane using energy, the process is most specifically called active transport, which requires ATP and transports molecules against their concentration gradient.
Step-by-step explanation:
If molecules are being pumped across a membrane using energy, the process is most specifically called active transport. During active transport, molecules move from an area of low concentration to an area of high concentration, which goes against the concentration gradient. This type of transport requires energy, usually in the form of ATP (adenosine triphosphate).
On the other hand, passive transport, which includes osmosis and facilitated diffusion, involves the movement of molecules across the cell membrane without the use of cellular energy. Molecules move from an area of higher concentration to an area of lower concentration, following the concentration gradient.
Since the question specifies that energy is being used to pump the molecules, the correct answer is D) Active transport.