NO.PZ2015122802000095
问题如下：
With respect to rational and irrational investment decisions, the efficient market hypothesis requires:
选项：
A.only that the market is rational.
B.that all investors make rational decisions.
C.that some investors make irrational decisions.
解释：
A is correct.
The efficient market hypothesis and asset-pricing models only require that the market is rational. Behavioral finance is used to explain some of the market anomalies as irrational decisions.
考点：Efficient Capital Market And Its Forms
等学完行为金融就会知道人是非理性的，我们很难假设个体是理性的。但是市场反应的是人们的平均表现，因此在有效市场假说中我们只假设市场是有效的。请把这道题当做结论记忆就好。
既然不能保证所有人都是理性的，那么C选项为什么不对？
