Which statement best explains the effect on membrane permeability of cholesterol and/or temperature?
a. Adding cholesterol increases permeability because its steroid rings decrease the density of the hydrophobic membrane interior.
b. Adding cholesterol reduces permeability because its steroid rings fill gaps in the hydrophobic membrane interior.
c. Increasing temperature increases permeability because it increases the strength of hydrophobic interactions in the membrane interior.
d. Adding cholesterol increases permeability because its steroid rings increase the density of the hydrophobic membrane interior.
