Question

which of these statements best describes the function of the cell membrane?
it prevents substances from leaving the cell
it prevents substances from entering the cell
it controls which substances enter and exit the cell
it allows things to freely enter and exit the cell

Explanation:

The cell membrane is a selectively permeable structure. It does not prevent all substances from entering or leaving (ruling out the first two options) nor does it allow free movement (ruling out the fourth). Instead, it regulates the passage of substances, controlling which enter and exit the cell.

Answer:

C. it controls which substances enter and exit the cell (assuming the third option is labeled C; if the original options had different labels, adjust accordingly based on the third option's text "it controls which substances enter and exit the cell")