Question

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

Explanation:

Facilitated diffusion is a type of passive transport (so it does not require energy input like ATP). It moves substances (such as polar or charged molecules that can't easily cross the lipid - bilayer) down their concentration gradient (from an area of higher concentration to an area of lower concentration). And it requires the help of transport molecules (either channel proteins or carrier proteins). So all the given options (moving with the concentration gradient, being a form of passive transport, and requiring the help of a transport molecule) are correct characteristics of facilitated diffusion.

Answer:

all of these.