Answer: C
Explanation: Smaller single-celled organisms have a high surface area to volume ratio, which allows them to rely on oxygen and material diffusing into the cell (and wastes diffusing out) in order to survive. The higher the surface area to volume ratio they have, the more effective this process can be.
The solute can move "downhill," from districts of higher to lower fixation, depending on the specificity of the protein bearer to go through the film. This procedure is called uninvolved transport or encouraged dissemination, and does not require vitality.
