A cell membrane is composed of a lipid bilayer in which many kinds of proteins are embedded. These proteins use energy to actively transport certain particles into and out of the cell. Which example BEST illustrates the condition in which molecules move across the cell membrane through active transport?

A. When molecules need to move from an area of lower concentration to an area of higher concentration.

B. When the cell wall is damaged or genetically modified and molecules cannot enter or leave the cell.

C. When molecules need to move from an area of higher concentration to an area of lower concentration.

D. When the amount of water is higher inside of the cell as compared to the area surrounding the cell.