An investor chooses a portfolio that maximizes a mean-variance objective function. [Notation: ro: risk-free interest rate; : expected rate of return on asset j; o;: standard deviation of return on asset j: up: expected rate of return on the optimum portfolio P; op: standard deviation of the return on the optimum portfolio P: 0p: covariance between the rate of return on asset j and portfolio P.] At the investor's optimum, the following condition holds for every asset, j: A. (-ro)/3 = (up-ro)/op. B. (1y-To)/0p= (p - To)/0. C. -To)/0,= (-ro)/a,, for every pair of assets i and j (i j). D. (ro)/0,= (p - To)/0p. E. None of the above. Select one: A. --- B. C. D. E.