I’d say A is probably the correct answer , but if not A , then definitely B.
For the answer to the question above, it is <span>Considered as a cell shaped like a perfect </span>sphere<span>: it has a surface area of 4πr </span>2<span>, and a volume of (4/3)πr </span>3<span>. The surface-to-volume ratio of a </span>sphere<span> is 3/r; as the cell gets bigger, its surface-to-volume ratio decreases, making diffusion less efficient.</span>
That would be the concentration gradient of hydrogen ions(protons). See the attached pic:)
