Answer:
C. away from the area where it is more concentrated.
Explanation:
If a molecule is moving across a cell membrane w/o using the cell's energy, it is diffusion, which is defined as the movement of a substance from higher to lower concentration. Diffusion never requires energy, whether it is facilitated or not, as clustered molecules and/or atoms simply want to get the heck away from each other if in too high concentration in a single place. The type of molecular movement across a cell membrane that would require the cell's energy would be active transport, which often requires ATP or GTP and works against a concentration gradient.
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