Question

facilitated diffusion can be described as... moving with the concentration gradient. requiring the help of a transport molecule. a form of passive transport. all of these.

Explanation:

Facilitated diffusion is a type of passive transport. Passive transport means substances move without the use of energy. In facilitated diffusion, substances move with the concentration gradient (from an area of higher concentration to an area of lower concentration). Also, it requires the help of transport molecules (such as channel proteins or carrier proteins) to move substances (usually polar or large molecules that can't pass through the lipid - bilayer easily) across the cell membrane.

Answer:

all of these.