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

• A. It buffers membrane fluidity and stability by preventing extreme packing at low temperatures and excessive fluidity at high temperatures.
• B. It forms aqueous pores that allow large polar molecules to diffuse freely across the membrane.
• C. It serves as the main covalent cross-linker that permanently locks phospholipid tails together.
• D. It provides most of the membrane’s selective ion transport by functioning as an ATP-driven pump.

Answer: (A)