Answer:
C. Active transport
Explanation:
Active transport is the process by which cells introduce substances against their osmotic potential. It is the opposite of diffusion, where substances move through membranes without the need of extra energy, as they follow a favorable osmotic potential towards equilibrium.
Active transport needs special proteins on the membranes to perform the task, whereas diffusion may need them (facilitated diffusion) or not (osmosis) depending on the size of the incoming molecules and the membrane's permeability.
