4. What is/are the difference(s) between passive diffusion and facilitated diffusion?
(A) Passive diffusion does not require protein transporters, while facilitated diffusion does.
(B) Passive diffusion does not require ATP hydrolysis, while facilitated diffusion does.
(C) Passive diffusion does not display saturation behavior, while facilitated diffusion does.
(D) All of the above
(E) A and C