Why some takeover defenses cannot be created once the intention of corporate rider to acquire the target becomes clear? a. Because the US regulatiors wants to protect (to a certain extent) the aquirer shareolders b. Because of the need for the target shareholders to be also protected from their own managers. c. Because the M&A market is a competitive market. d. Because some the very restrictive defense mechanisms are to complex to implement and would delay to much the proxy fight