How does the saturation level of lipid tails affect membrane fluidity?

• A. Saturated lipid tails decrease fluidity due to the presence of double bonds.
• B. Saturated lipid tails increase fluidity due to the absence of double bonds.
• C. Unsaturated lipid tails decrease fluidity due to the absence of double bonds.
• D. Unsaturated lipid tails increase fluidity due to the presence of double bonds.

Answer: (D)