Answer: The correct answer is -
It prevents harmful substances from entering a cell.
Explanation:
Cell membrane is a selectively permeable, protective layer that is present surrounding the cytoplasm of all cells of living organisms. It allows the entry and exit of only certain substances
It does not allow the harmful substances to enter inside the cell and at the same time, the useful substances to exit the cell. Due to this, it is also known as selectively permeable membrane.
Thus, last option is the right answer.
