Which of the following is a guideline for apparatus rider safety?

The correct guideline for apparatus rider safety emphasizes that firefighters should never ride on the tailboard, front bumper, or running boards of any moving apparatus. This rule is in place due to safety concerns. Riding in these areas exposes firefighters to serious risks, including falling off the apparatus, being struck by other vehicles, or becoming injured due to the apparatus's movement or sudden stops. These positions do not provide the structural safety and support needed during emergency response operations.

The other options, while they might promote some level of safety, do not capture the fundamental guideline aimed at protecting personnel while they are riding on the apparatus in a moving situation. For instance, wearing reflective vests is important for visibility, but it does not address the inherent risks involved with unsafe riding positions. Similarly, conducting safety checks every 15 minutes is a best practice for overall operation but does not pertain specifically to the safety of those riding on the apparatus. Ensuring that every firefighter has an individual radio is beneficial for communication but does not directly relate to the core issue of safety while riding.