For each of the following pairs of investments, indicate which would always be preferred by a rational investor (assuming that these are the only investments available to the investor): a. Portfolio A Portfolio B r = 109 r = 68 0 = 12 0 = 12% Portfolio A Portfolio B Preference Indeterminate r = 118 b. Portfolio C Portfolio D 0 = 128 0 = 68 Portfolio C Portfolio D Preference: Indeterminate c. Portfolio E Portfolio F r = 16% r = 16% 0 = 209 0 = 148 Portfolio E Portfolio F Preference: Indeterminate