Which of the following is one example of active fire protection?

Active fire protection refers to systems that require some form of action, whether automatic or manual, to suppress or control a fire. This includes various fire suppression methods that function during a fire event to actively combat the flames and minimize damage.

Foam systems are a prime example of active fire protection because they can be deployed to extinguish fires by cooling the flames and smothering the surface of flammable liquids, effectively preventing oxygen from fueling the fire. These systems can range from portable extinguishers to large fixed installations that engage automatically.

In contrast, while fire walls and fire-resistant coatings provide passive protection by preventing the spread of fire and protecting structural integrity, they do not actively engage with flames. Thermal insulation serves a similar role in protecting structures but does not involve action during a fire. Therefore, foam systems are the correct choice because they embody the active nature of fire protection systems.