Final answer:
Searching for hidden fires is a primary function of overhaul, where firefighters ensure that the fire is completely put out by checking for hidden fire pockets.
Step-by-step explanation:
Searching for hidden fires is a primary function of overhaul. During overhaul, firefighters perform the important task of ensuring that the fire has been completely extinguished, which includes finding hidden fire pockets that may reignite. Firefighters must carefully examine the scene for smoldering embers and hidden fires behind walls or above ceilings to prevent potential rekindling. This phase occurs after the main body of the fire is out, and is critical to the safety of both the property and the firefighters. Sizeup is an assessment of the situation to determine the strategy for fire suppression, salvage focuses on saving property and preventing further damage, and fire investigation is the determination of the cause of the fire.