By controlling what enters and leaves a cell, the cell membrane A. aids in maintaining homeostasis within the cell. B. aids in maintaining homeostasis outside of the cell. C. aids in maintaining osmosis within the cell. D. aids in maintaining osmosis outside of the cell.

By controlling what enters and leaves a cell, the cell membrane A) aids in maintaining homeostasis within the cell. Homeostasis is the process by which organisms maintain life through eating, growing, and living in variable conditions. It would not make sense to answer B) because organisms do not control the homeostasis of their external environment. D) also would not be correct because cell's do not control osmosis in the external environment. The membrane does not control osmosis because osmosis is generally a random process of molecular diffusion whereas the membrane acts in a conscious and controlled way.