Qil: Which of the following best explains why both plant and animal cells contain cell membranes? A Both animal and plant cells have cell membranes to act as the site of protein synthesis. B Both animal and plant cells have selectively permeable cell membranes to control which substances can enter and leave the cell. C Both animal and plant cells have cell membranes to store and organize their genetic material. D Both animal and plant cells have cell membranes that contain cellulose to provide structure and support for the cell. E This is incorrect; only animal cells have cell membranes.