Answer the following questions and explain your answers in details:

a. Explain why any test of market efficiency is always a joint test.

b. Very risky stocks on average yield higher returns than relatively safe stocks. Is this a violation of market efficiency?

c. Stocks that have appreciated unusually in the recent past continue to do so. Is this a violation of market efficiency?

d. A successful firm like Microsoft has consistently generated large profits for years. Is this a violation of market efficiency?

e. You can earn abnormal returns by buying stocks in December and selling them in January. Which form of market efficiency does this strategy violate?