问题如下：
Compared with broad-market-cap weighting, the international equity strategy suggested by McMahon is most likely to:
选项：
A. concentrate risk exposure.
B. be based on the efficient market hypothesis.
C. overweight stocks that recently experienced large price decreases.
解释：
A is correct. Compared with broad-market-cap weighting, passive factor-based strategies tend to concentrate risk exposure, leaving investors vulnerable during periods when the risk factor (e.g., momentum) is out of favor.
李老师解释里面的alternative beta是什么，不会就是指其他的因子吧？有这个叫法么，和集中的关系是？
