Biology

The correct answer is: B.Cell membrane

Explanation:

If you were a "bad guy" trying to sneak into an animal cell, the cell membrane would be the primary barrier trying to stop you. The cell membrane acts as a "gatekeeper," controlling what enters and exits the cell. It is selectively permeable, meaning it can prevent unwanted substances from entering the cell and can also actively regulate the movement of molecules using proteins embedded in the membrane.

Why the other options are incorrect:

A.Nucleus: The nucleus is the control center of the cell that contains genetic material (DNA), but it is not th...