Answer:
Active transport
Explanation:
Diffusion occurs when molecules move from an area of high concentration to a low concentration until equilibrium is achieved. This does not require energy because it is a spontaneous process. This also included osmosis when there’s a difference in the concentration of solutions across a semipermeable membrane, water molecules move from the low concentration the solution to high concentration until the two solutions are isotonic to each other.
To move molecules against a concentration gradient, energy must be expended. In cell this is through the energy of ATP molecules.
