What is the key factor of an experiment that would distinguish pore-mediated diffusion (e. g., by gramicidin) from carrier-mediated diffusion (e. g., by valinomycin)?

A. The key factor is to allow the concentration of membrane lipids to be higher than ionophores under conditions where the bilayer is fluid, and then drop the temperature below the Tm of the bilayer.
B. The key factor is to allow the concentration of membrane lipids to be lower than ionophores under conditions where the bilayer is fluid, and then increase the temperature below the Tm of the bilayer.
C. The key factor is to allow the membrane lipids and ionophores to equilibrate under conditions where the bilayer is fluid, and then drop the temperature below the Tm of the bilayer.
D. The key factor is to allow the membrane lipids and ionophores to equilibrate under conditions where the bilayer is fluid, and then increase the temperature above the Tm of the bilayer.