问题如下：
Returns on asset classes are best described as being a function of:
选项：
A.the failure of arbitrage.
B.exposure to the idiosyncratic risks of those asset classes.
C.exposure to sets of systematic factors relevant to those asset classes.
解释：
C is correct.
Strategic asset allocation depends on several principles. As stated in the reading, "One principle is that a portfolio’s systematic risk accounts for most of its change in value over the long run." A second principle is that, "the returns to groups of like assets… predictably reflect exposures to certain sets of systematic factors." This latter principle establishes that returns on asset classes primarily reflect the systematic risks of the classes.
这道题考的是什么呢？没明白
