Question

a molecule moves down its concentration gradient using a transport protein in the plasma membrane. this is an example of view available hint(s) exocytosis. facilitated diffusion. active transport. diffusion. endocytosis.

Explanation:

Facilitated diffusion is the passive movement of molecules down their concentration gradient with the help of transport proteins in the plasma - membrane. Exocytosis and endocytosis are for bulk transport. Active transport moves molecules against the concentration gradient. Simple diffusion does not require a transport protein.

Answer:

B. facilitated diffusion