4) A risk-averse investor is evaluating the following investments: Portfolio A: E(RA)= 9 percent, o(RA) = 6 Portfolio B: E(RB) = 9 percent, o(R) = 7 Portfolio C: E(Rc)= 12 percent, o(Rc) = 10 a. Explain the choice among Portfolios A, B, and C using the Markowitz decision rule. b. Explain the choice among Portfolios A, B, and C assuming that borrowing and lending at a risk-free rate of Rx = 2 percent is possible