Fires caused by spontaneous combustion are most likely to occur in which of the following areas?

Fires caused by spontaneous combustion are most likely to occur in oily waste rag storage areas. This happens because organic materials, especially those that are oily or have been contaminated with flammable substances, can generate heat as they oxidize. If these materials are piled together or stored in a confined area, the heat may not dissipate effectively, leading to an increase in temperature. When the temperature reaches a certain point, it can ignite the materials, resulting in a fire.

In contrast, while fuel storage tanks can pose fire hazards, spontaneous combustion is less common due to typically regulated conditions to prevent such incidents. Boiler rooms and electrical rooms, although they have their own specific fire risks associated with equipment and materials used, do not commonly experience spontaneous combustion in the same way that oily waste rag storage does. Hence, oily waste materials are particularly prone to these types of fires due to their chemical properties and the conditions under which they are often stored.