What materials are prohibited in or around powder magazines?

The correct choice identifies rubbish or combustible materials as prohibited in or around powder magazines due to safety regulations. Powder magazines are specialized storage facilities designed to house explosive materials safely. The presence of combustible materials poses a significant risk because they can easily ignite under certain conditions, potentially leading to catastrophic explosions.

Combustible materials can include things such as trash, flammable liquids, or any other items that could catch fire. Maintaining a clean and controlled environment around these storage facilities is crucial for minimizing the risk of fire or explosion.

While non-combustible materials, heavy machinery, or electronic devices may have their own regulations and considerations, they do not carry the same direct risk as combustible materials in the context of storing explosives.