Which of the following describes the plasma membrane?

a) a double layer of protein enclosing the plasma

b) a single-layered membrane that surrounds the nucleus of the cell

c) the phospholipid bilayer surrounding the cell

d) a membrane composed of tiny shelves or cristae

The correct answer is letter C

All cells have a structure called a plasma membrane, which acts as a barrier to prevent both the exit of cell content into the medium and the flow of any particle into the cell. This characteristic therefore shows an important ability to select the structure, which can vary from 7 to 10 nm in thickness.