Why Does Active Transport Require ATP

Multiple Choice

Why does active transport require ATP?

A) An input of energy is needed to speed up the rate of facilitated diffusion.
B) An input of energy is needed to allow the movement of molecules from an area of low concentration to one of higher concentration.
C) An input of energy is needed to maintain the conformation of transport proteins.
D) An input of energy is needed to both speed up the rate of facilitated diffusion and maintain the conformation of transport proteins.