Students in science class were asked to come up with real-world examples that were similar to a selectively permeable membrane in a cell. Which example below best models a selectively permeable membrane?

A. An open gate that allows all animals to move in and out of the pasture

B. A wall that separates one room of a house from another

C. A roadblock that will not allow cars to move through

D. A window screen that allows air to move through but insects are left outside