Mary Talked to Several Stockbrokers and Made the Following Conclusions

Multiple Choice

Mary talked to several stockbrokers and made the following conclusions. Which, if any, of her conclusions are correct?

A) It is relatively easy to reduce firm-specific risk by increasing the number of companies one holds stock in.
B) Stock prices, even if not exactly a random walk, are very close to it.
C) Some people have made a lot of money in the stock market by using insider information, but these cases are not contrary to the efficient markets hypothesis.
D) All of Mary's conclusions are correct.