NO.PZ2015121801000073
问题如下：
Compared to the efficient frontier of risky assets, the dominant capital allocation line has higher rates of return for levels of risk greater than the optimal risky portfolio because of the investor’s ability to:
选项：
A.lend at the risk-free rate.
B.borrow at the risk-free rate.
C.purchase the risk-free asset.
解释：
B is correct.
The CAL dominates the efficient frontier at all points except for the optimal risky portfolio. The ability of the investor to purchase additional amounts of the optimal risky portfolio by borrowing (i.e., buying on margin) at the risk-free rate makes higher rates of return for levels of risk greater than the optimal risky asset possible.
请问为什么不是c？CAL不是optimal risky asset and risk free asset连在一起的线吗？
