Answer: Limited Surface area - Volume ratio
Explanation:
Cells in various organisms usually have the same size be it a blue whale or an earthworm, a Human or a mouse or an Elephant and a squirrel. This is down to the way the cell is structure.
The Cell needs to absorb nutrients to survive while getting rid of waste material. For that to happen it needs an adequate surface area. The problem is that as the cell absorbs more nutrients thereby increasing in volume, this rise in volume occurs at a faster rate than the cell can increase its surface area so the surface area will keep shrinking.
Therefore, in order to have enough surface area to keep up the process of absorption and excrement, the cell will stop growing at the certain point and this process is similar in most if not all organisms.
Sublingual, IV, IM, insufflation, Skin absorbtion, Plugging, inhalation, eye absorbtion, and of course, swallowing. Discounting Skin and eye absorbtion, youve got 7 so i would go with that.
