Which benchmark signifies that all primary search efforts are clear?

The benchmark that signifies all primary search efforts are clear is "Secondary All Clear." This term indicates that the secondary search of the structure has been completed, and no victims or occupants are found in the areas searched, confirming that the environment is safe.

Conducting a secondary search is essential in fire operations to ensure that all areas of a building have been thoroughly checked after the initial primary search. The primary search focuses on locating and rescuing any victims swiftly, while the secondary search is more detailed to ensure that no one has been overlooked. Declaring "Secondary All Clear" means that the search operations are comprehensive, contributing to the safety of both firefighters and civilians.

The other options represent different stages or outcomes in fire operations, but they do not specifically confirm that all primary searches have been completed. These benchmarks serve different purposes, like managing the overall incident or preparing for different operational stages but do not directly indicate the completion of primary search efforts.