Which of the Following Statements Is True

Which of the following statements is true?

A) Tonicity refers to the effect of penetrating solutes on cell volume.
B) A one molal solution contains 1 mole of solute per liter of solution.
C) To accommodate larger molecules, membrane channels have an average diameter of 1 - 1.5 nanometers.
D) Carrier proteins span the membrane and can undergo shape changes.
E) Aquaporins regulate solute movement across membranes.