What is the required countdown before launching a high-power rocket?

The correct countdown before launching a high-power rocket is 5 seconds. This specific countdown is crucial for ensuring that all systems are functioning properly and that safety checks are completed before ignition. A countdown allows for a structured approach to launch, providing time for operators to confirm that everything is in order and to address any potential issues that may arise.

During this countdown period, a variety of checks can be made, such as confirming the launch site is clear, ensuring all telemetry systems are operational, and verifying that the rocket is secured and stable. It also gives team members time to get to a safe distance from the launch vehicle. This practice aligns with safety protocols and ensures that the launch can proceed without unforeseen complications.

The other options present longer or shorter countdowns, but they do not align with established safety norms and operational practices within the high-power rocketry community.