Which action is crucial if firefighters need to protect an advancing team due to fire products?

Setting up a second line is crucial in protecting an advancing team due to fire products because it provides an additional layer of defense against heat and smoke, which are significant hazards in firefighting operations. By deploying a second line, firefighters can create a safer environment for the advancing team, allowing them to maneuver more effectively and carry out their tasks while minimizing exposure to dangerous conditions.

This action can also help to control the fire's progression, ensuring that the team moving forward has an alternative route of escape and immediate access to water for suppression if needed. The additional line can act as a backup, ensuring continuous protection not only for the team advancing into hazardous areas but also for any civilians or property that might still be at risk.

In contrast, other options may contribute to a firefighting strategy but do not directly provide the same level of protection to the advancing team. For instance, spraying water can suppress flames but may not sufficiently shield the team from the effects of fire products. Calling for backup is essential for support and additional personnel but does not directly mitigate immediate threats. Establishing a perimeter is important for controlling the scene and preventing the fire from spreading but does not focus on directly protecting those who are engaged in active firefighting efforts.