Which statement about the cell membrane is true?

A. It contains cellulose and sugars that are involves I'm communication.

B. It us present in animals cells only.

C. It is rigid and elastic fur supporting the cell's shape.

D. It prevents harmful substances from entering a cell.

D is the correct answer. The cell membrane separates the inside of the cell from its external environment. It allows the movement of some molecules in and out of the cell and controls the movement of all other substances in and out of the cell. Its basic function is protection against harmful substances that may want to enter the cell.