$2$ Efficient markets

Are the following statements true or false? Explain your answer in no more than two sentences.

$($a$)$ Good News, Inc., just announced an increase in its annual earnings, yet its stock

price fell. This may be consistent with the efficient markets hypothesis.

$($b$)$ If the stock market is efficient in the semi$-$strong sense, there should be$,$ on average,

no increase in a company$$s stock price before the company announces good news

about its business.

$($c$)$ If risky stocks on average have higher returns than safe stocks, the efficient market

hypothesis may still hold.

$($d$)$ The efficient markets hypothesis must fail, because lots of investors do crazy things

in the market.