Which action may not be used as a defense according to TC Rules 31-35?

The correct answer is related to the concept of a "poison pill." A poison pill is a strategy used by companies to make themselves less attractive to potential hostile takeovers. While it is a tactical measure to protect against such events, it is generally not recognized as a valid defense under the TC Rules 31-35. These rules outline permissible defenses that can be employed when facing a takeover attempt, and the poison pill could be seen as a maneuver that contradicts the intentions of these regulations.

In contrast, actions such as a shareholder vote, the hiring of a white knight (a friendly company that acquires a target company to prevent a hostile takeover), and the preparation of audited defense documents are considered more legitimate or accepted forms of defense according to TC Rules. Each of these actions allows companies to engage in protective measures within the scope of regulatory compliance, which is not the case with a poison pill strategy.