Help on efficient market

19.In an efficient market, prices appear to move randomly because A. investors do not process new information correctly. B. only new information affects stock prices. C. insider trading has an unpredictable effect on stock prices. D. the number of investors who can forecast prices correctly is too small to have any effect. 20.Which one of the following activities is likely to be useful if the market is only weak form efficient? A. attempting to find the best times to buy and sell B. attempting to find repeating pattern in stock price behavior C. attempting to determine if stock prices have upward or downward momentum D. studying financial, economic and industry information about a company 21.Followers of the efficient market hypothesis believe that A. very few investors actually analyze or evaluate stocks before they make a purchase decision. B. the needed information to assess the market is available only to corporate insiders. C. investors react quickly and accurately to new information. D. individual traders can have a significant impact on the price of a security