What materials are not allowed to be stored in exits or corridors?

The correct choice highlights that any flammable or obstructive materials are not permitted to be stored in exits or corridors due to safety regulations. This is crucial because exits and corridors are designated for safe egress during an emergency. Storing flammable materials can significantly increase the risk of fire hazards, while obstructive materials can impede safe evacuation routes, which can lead to dangerous situations in the event of a fire or other emergency.

Exits are meant to be clear to ensure that individuals can evacuate the building quickly and safely. By restricting flammable and obstructive items from these areas, fire safety regulations prioritize the protection of lives and promote an effective escape path. Fire codes and regulations typically mandate that exits and corridors must remain unobstructed and free of any materials that could pose a risk during emergencies.

In contrast, the other options may include items that do not inherently present the same level of risk when stored in these critical areas, although storing any material in exits or corridors is generally discouraged. It's important to maintain these pathways for safety, which is why the presence of flammable or obstructive materials is specifically highlighted as a violation of fire safety standards.