The (mean, standard deviation) pair of returns of three portfolios comprising of risky stocks are given below. It is known that only one of them is efficient under Markowitz Model 1 (i.e. the Markowitz model that involves only risky assets), and the other two are not efficient. Identify the efficient portfolio and state the reason. (M1,01) = (1%, 2%), (u2,02) = (2%,3%), (43,03) = (3%, 2%)