In the context of the lipid bilayer, what is the primary role of cholesterol in animal cell membranes?

• A. It buffers membrane fluidity by reducing permeability and preventing the membrane from becoming too fluid at high temperatures or too rigid at low temperatures.
• B. It functions as an integral channel protein that selectively transports ions across the membrane.
• C. It forms covalent cross-links between phospholipid tails to permanently stabilize the bilayer.
• D. It serves as the main energy-storage lipid within the membrane by being polymerized into glycogen-like chains.

Answer: (A)