When fueling a placarded vehicle, where must someone always be?

Answer: B — At the nozzle controlling the fuel flow

When fueling a placarded vehicle, it is essential for someone to be at the nozzle controlling the fuel flow. This requirement is a critical safety measure to prevent spills, overfilling, and potential ignition sources that could lead to fire or explosion, especially considering the nature of hazardous materials. Being at the nozzle allows the individual to respond immediately to any issues that may arise during the fueling process, such as a spill or an unexpected reaction. Monitoring the fuel gauge from the pump, being inside the vehicle, or waiting in the cabin does not provide the same level of immediate oversight or control, which is crucial for maintaining safety standards when handling hazardous materials. Therefore, staying at the nozzle ensures that proper protocols are followed while fueling, safeguarding both the operator and the surrounding environment.