Answer:
B.
Explanation:
The lettered structure B, is a cell membrane.
The cell membrane, also known as plasma membrane is the outer thin enclosure that surrounds a cell. It serves a s physical barrier that separates the cell structures from the surrounding environment of the cell.
This cell membrane is permeable, and performs one of the important function of the cell which is the excretion of most of the wastes from the cell.
The cell member is the medium fro exchange of substances between the cell and the its environment.
