What is a possible hazard of keeping oil rags in the boiler room?

Keeping oil rags in the boiler room can lead to spontaneous combustion due to the nature of the materials involved. Oil-soaked rags, especially if they are piled up, can undergo exothermic oxidation, where the heat generated by the oxidation process may not dissipate quickly enough. This can occur when the rags are stacked in a way that limits airflow, causing the temperature to rise. Once it reaches a certain threshold, the rags can catch fire without an external ignition source, resulting in a hazardous situation in an environment already filled with combustible materials.

Other options may describe potential hazards in a boiler room, such as corrosion from humidity or electrical fires, but spontaneous combustion is specifically related to the storage of oil-soaked materials. Thus, it poses a significant and direct risk in this context.