问题如下：
With respect to capital market theory, an investor’s optimal portfolio is the combination of a risk-free asset and a risky asset with the highest:
选项：
A. expected return.
B. indifference curve.
C. capital allocation line slope.
解释：
B is correct.
Investors will have different optimal portfolios depending on their indifference curves. The optimal portfolio for each investor is the one with highest utility; that is, where the CAL is tangent to the individual investor’s highest possible indifference curve.
请问，EF线与无差异曲线切点是highest indifference curve，题目里说CAL与无差异曲线切点也是highest indifference curve，这两个切点是一个点吗？
