According to the relationship identified, the _____ the population protected by a fire service, the ________ the number of fireground injuries per 100 fires.

The correct choice illustrates a fundamental relationship in fire service operations. The observation that a larger population protected by a fire service correlates with a higher number of fireground injuries per 100 fires can be attributed to several factors.

When fire services are responsible for a larger area or a denser population, they often encounter more complex and challenging situations during emergencies, which could result in increased risk and injuries among firefighters. Additionally, more incidents in high-population areas can lead to more response scenarios, contributing to a higher likelihood of injuries in the field.

Essentially, as the population size grows, the demands on fire service resources and the nature of emergency responses can become more elevated and complicated. This demands not only more frequent interventions but also exposes firefighters to greater risks, hence the correlation to a higher number of injuries. This understanding emphasizes the need for robust training, resource allocation, and safety protocols to mitigate risks associated with firefighting in densely populated locations.