Which Statement Regarding the Efficient Markets Hypothesis Is True

Which statement regarding the efficient markets hypothesis is true?

A) The efficient markets hypothesis suggests that the market does not price stocks fairly; hence, managers should make decisions based on the premise that firms' stocks are undervalued or overvalued.
B) An individual who has information about past stock prices would be able to profit from this information if weak-form market efficiency exists.
C) For the efficient markets hypothesis to hold true, every individual investor must be "rational."
D) Semistrong-form market efficiency means that stock prices reflect all public, but not necessarily all private, information.