In Facilitated Diffusion, a Molecule Is Moved

In facilitated diffusion, a molecule is moved

A) against its concentration gradient while Na is moved with its concentration gradient.
B) against its concentration gradient with the assistance of a protein carrier molecule, but no energy is required.
C) down its concentration gradient with the assistance of a protein carrier molecule, and no energy is required.
D) against its concentration gradient with the assistance of a protein carrier molecule and requires energy.
E) with its concentration gradient while Na is moved against its concentration gradient.