Which of the following is an example of direct firefighting?

Using fire extinguishers is a clear example of direct firefighting because it involves taking immediate action to extinguish or control a fire right at the source. Fire extinguishers are designed specifically for this purpose, allowing individuals to apply a suppressive agent directly onto the flames to halt the combustion process. This method is typically employed in scenarios where small or manageable fires pose a threat, and rapid response is crucial to prevent escalation.

In contrast, creating firebreaks, shutting off gas supply, and restricting airflow are more indirect methods aimed at preventing a fire from spreading or mitigating its impact rather than extinguishing an active fire. Firebreaks involve clearing vegetation and other combustible materials to stop fire progression, manipulating the environment rather than fighting the fire directly. Shutting off the gas supply reduces fuel availability to a fire, which is often part of a broader strategy to control a situation. Similarly, restricting airflow is a tactic used to deprive a fire of oxygen as it develops, thus indirectly influencing its behavior rather than directly suppressing it.

These other methods are important in fire prevention and control strategies but do not engage with the flames in a direct manner as using fire extinguishers does.