Agood model of the cell membrane would be

a) a chain link fence
b)a film of food wrap
c)a wall of stone and mortar
d)a river with objects floating in it

B. A film of food wrap

Explanation:

The membrane is supposed to keep the contents safe inside .Not many things can enter inside and almost nothing can come outside, this being the selectively permeable nature of the membrane.

The plasma membrane, or the cell membrane, provides protection for a cell. It also provides a fixed environment inside the cell. And that membrane has several different functions. One is to transport nutrients into the cell and also to transport toxic substances out of the cell. Another is that the membrane of the cell, which would be the plasma membrane, will have proteins on it which interact with other cells. Those proteins can be glycoprotein, meaning there's a sugar and a protein moiety, or they could be lipid proteins, meaning there's a fat and a protein. And those proteins which stick outside of the plasma membrane will allow for one cell to interact with another cell. The cell membrane also provides some structural support for a cell. And there are different types of plasma membranes in different types of cells, and the plasma membrane has in it in general a lot of cholesterol as its lipid component. That's different from certain other membranes within the cell. Now, there are different plants and different microbes, such as bacteria and algae, which have different protective mechanisms. In fact, they have a cell wall outside of them, and that cell wall is much tougher and is structurally more sound than a plasma membrane is.