What happens if stoppings are not constructed using incombustible materials?

The correct answer highlights a critical safety concern in underground mining operations. If stoppings, which are barriers used to control the airflow and isolate sections of the mine, are not constructed using incombustible materials, they can significantly increase the risk of fire.

Using combustible materials for stoppings can create a scenario where, if a fire were to ignite in the mine, these materials would easily catch fire, leading to rapid spread of the fire and making it difficult to contain. This can put miners' lives at risk and complicate evacuation efforts. It is essential for stoppings to be made of incombustible or fire-resistant materials to mitigate the risk of combustion and ensure a safer working environment.

While other options may relate to different aspects of mine safety and operations, they do not address the pressing issue of fire safety directly associated with the materials used in constructing stoppings. The use of incombustible materials is a fundamental requirement to prevent the exacerbation of fire hazards in underground mines.