Which of the following statements is TRUE according to the theory of the 'efficient market hypothesis'?

Select one:

a. Since securities are fully and fairly priced, it follows that investors should accept the same level of stock returns regardless of the risk tolerance.

b. It has been proven that shares are not fully and fairly priced, so investors should spend time searching for mispriced (overvalued or undervalued) securities.

c. Changes in investors' assessments of a firm's outlook lead to changes in the supply and demand for its shares, which can cause a change in the price of the shares.

d. Securities are typically in equilibrium, meaning they are fairly priced and their expected returns are greater than their required returns.

e. At any point in time, security prices do not fully reflect all public information available about the firm and its securities, and these prices react very slowly to new information.