Which of the following is NOT relevant to facilitated transport across biological membranes?

A) An ionophore is a carrier protein that increases the permeability of a membrane to ions.
B) Some permeases can transport their substrates in both directions.
C) A symport will transport two molecules in the same direction across a membrane.
D) ATP hydrolysis is required.
E) An antiport will move substrates in opposite directions across a membrane.