If you are loading or unloading explosives, what must you ensure?

Answer: B — That cargo heaters have been disabled

Ensuring that cargo heaters have been disabled during the loading or unloading of explosives is crucial for safety. The presence of heat can lead to unintended ignition or reaction of explosive materials, which can be catastrophic. This is particularly important because explosives often have specific temperature thresholds that can trigger a reaction. Therefore, disabling cargo heaters is a necessary precaution to maintain a safe environment while handling such hazardous materials. Cargo doors being secure, having fire extinguishers within reach, or the presence of security personnel are also important safety considerations, but they do not directly relate to the specific need to prevent ignition risks during the handling of explosives. Disabling heaters directly addresses a potential hazard that could lead to severe consequences if not managed properly.