Answer: The relationship between its volume and surface area
Explanation: Most cells are specially designed to maximize their surface area to volume ratio. This is because cells want as much surface area as possible in order to maximize the level of gaseous diffusion and the area availiable for molecules to be brought into the cell. This improves chemical reaction efficiency, thus allowing the cell to be more efficient with its resources and time.
On the other hand, cells do not want too much volume. Having too much volume makes the transport of molecules within the cell more extensive in terms of distance, thus increasing resource cost. Diffusion would take longer to occur between the environment of the cell and the outside environment, and larger cells require more resources in order to perform their duties and survive.
Thus, in order for cells to be as efficient as possible, they need a very large surface area to volume ratio. In order to accomplish this, most cells tend to remain small. This is because larger cells have a smaller surface area to volume ratio, thus making them less effective at carrying out their functions and chemical reactions. Thus, cells are limited in size in order to maximize their surface area to volume ratios.