For each of the following scenarios, discuss whether abnormal returns exist from trading in the stock of the firm under the conditions that (1) the market is not weak form efficient, (2) the market is weak form but not semistrong form efficient, (3) the market is semistrong form but not strong form efficient, and (4) the market is strong form efficient. a) The stock price has risen steadily each day for the past 30 days. b) The financial statements for a company were released 2 days ago, and you discover an unusual revenue item in the income statement that has caused the true profitability of the firm to be understated. c) You find out that the senior management of a company has been buying a lot of the company's stock on the open market over the past week