Which of the following is NOT a necessary step when DCS Rules are activated?

The correct choice identifies a step that is not necessary when DCS (Dispatcher Control System) Rules are activated. The activation of DCS Rules requires various important processes to ensure safety and communication among involved parties during an incident.

Setting new signal lights immediately isn't typically a requirement because the focus during such situations is often on assessing the situation, ensuring proper communication, and following established protocols for safety. This includes gathering the crew for a briefing to ensure everyone is informed and on the same page, documenting the incident for record-keeping and analysis purposes, and obtaining authorization from the MTO (Manager of Train Operations) to ensure that actions taken align with operational and safety standards. Each of these steps contributes significantly to managing an incident effectively, while the immediate alteration of signal lights may not be part of the initial response protocols.