Assume that we are comparing the membrane fluidity of lipid bilayers. Rank the fluidity of the following bilayers in the order of increasing fluidity. Explain in each case the rationale behind your prediction

a. A lipid bilayer consisting of phosphatidyl choline molecules containing only 18-carbon saturated fatty acids

b. A lipid bilayer consisting of phosphatidyl choline molecules containing only 16-carbon saturated fatty acids

c. A lipid bilayer consisting of phosphatidyl choline molecules containing only 18-carbon unsaturated fatty acids having single double bond at position 9 in the fatty acid chain

d. A lipid bilayer consisting of phosphatidyl choline molecules containing only 18-carbon unsaturated fatty acids having single double bond at position 16 in the fatty acid chain