Answer:
The correct answer is 2. Cholesterol inhibits crystallization that would otherwise occur in membranes rich in unsaturated fatty acid.
Step-by-step explanation:
Cholesterol is a very important complex constituent of plasma membrane. It regulates the membrane fluidity at both high and low temperature.
Cholesterol acts as a bidirectional regulator of membrane fluidity because at high temperatures, it stabilizes the membrane and raises its melting point, whereas at low temperatures it intercalates between the phospholipids and prevents them from clustering together and stiffening.