Answer:
it is a cell.
Explanation:
the cell is the structural and functional unit of all living organisms
A cell membrane does not actually maintain homeostasis by itself. The term homeostasis refers to maintaining a relatively stable internal environment inside of a multi-cell organism. Since the internal environment is the interstitial fluid that is around each and every cell, then homeostasis has more to do with what is outside of a cell than what is inside of it. :)