Answer:
D. can control the transport of small molecules and ions.
Step-by-step explanation:
Bilayers are critical components of cell membranes. The lipid bilayer acts as a barrier to the passage of molecules and ions into and out of the cell. However, an important function of the cell membrane is to allow selective passage of certain substances into and out of cells.
The lipid bilayers are highly permeable to non-polar (fat-soluble) molecules. The permeability of the bilayers to polar (water soluble) molecules is very low, and the permeability is particularly low to large polar molecules. The permeability to charged molecular species (ions) is very low.