The Facilitated Diffusion of Ions from the Soil Solution into Root

The facilitated diffusion of ions from the soil solution into root cells requires

A) that the concentration of ions at the root cells be the same outside and inside.
B) that the concentration of ions outside the root cells be lower than the concentration inside.
C) the expenditure of ATP.
D) specific channel proteins in the membranes.
E) cellular respiration.