Which statement best describes a wet pipe sprinkler system?

A wet pipe sprinkler system is characterized by being always filled with water and is designed to activate automatically when a heat-sensitive element, such as a sprinkler head, detects a fire. This design allows for immediate water discharge upon activation, making it highly effective for quickly suppressing flames in indoor environments.

The effectiveness of a wet pipe system is primarily attributed to its readiness; water is already present in the system, eliminating delays associated with filling the pipes when a fire occurs. This contrasts with systems that rely on pressurized air or that are designed specifically for outdoor use, which serve different purposes and environments. Additionally, the system does not operate based on a drop in temperature but rather on the detection of heat from a fire, making it reliable for maintaining a prompt response to fire emergencies.