The answer is b it occurs in plant animals and bacteria
B. Animalia and Plantae, or animals and plants, are multicellular organisms.
B.
Special proteins are in charge of regulating the movement of substance through the double-membrane.
Your nerves send feedback to the brain to tell you what you are touching. I suppose that is a feedback mechanism. I dunno if it is entirely helpful.
In facilitated diffusion molecules only move with the aid of a protein in the membrane. Normal diffusion requires molecules to move through a special doorway
