Your friend, Molly, needs your help finding the average for a set of portfolio returns. They have calculated the returns (in %) as : month return 1 12.67 2 1.82 3 14.10 4 18.48 5 32.16 What is the arithmetic mean of these returns? Select one: a. 15.85% b. 15.64% c. 15.43% d. 0.00% e. insufficient information to determine f. 7.72% g. 79.23%