Final answer:
The correct answer is '4) all of the above' because sharp objects, active cargo heaters, or loose floor liners can all pose risks when loading explosives by potentially causing detonation or chemical changes.
Step-by-step explanation:
When loading explosives, one must check the cargo space for sharp objects or points, cargo heaters that could be turned on, and floor liners that are loose. Therefore, the answer to the question is 4) all of the above. It is crucial to eliminate any potential hazards which could lead to detonation or violent chemical change. Sharp objects may puncture or damage the explosives, heaters could increase the temperature to an unstable level, and loose floor liners could cause friction or shock - all posing serious risks.
It is also essential to understand safety guidelines such as keeping materials for raising fire ready, knowing how to handle flammable chemicals, where the fire safety equipment is located, and ensuring no open flames or heat sources are near the explosives unless specifically instructed.