Consider two investors, Will Smythe and Katherine Banning, who desire to invest 100 percent of their available funds in the optimal risky portfolio. Smythe invests his money in a portfolio with an expected return of 14 percent and a standard deviation of 10 percent. Banning invests her funds in a portfolio with an expected return of 19 percent and a standard deviation of 12 percent. Which of the two investors has invested their funds in the optimal portfolio（）
A. Smythe, since his portfolio has minimized total risk.
B. Banning, since the expected return per unit of risk is higher for her investment.
C. Both, since the optimal portfolio depends on an investor’s individual utility function.
参考答案：C
解析：
By definition, the optimal portfolio is the point of tangency between the efficient frontier and the utility function of a particular investor. Since every investor has his or her own set of utility curves (based on their attitudes toward risk and return), every investor could have a different optimal portfolio.