Under which circumstance should command abandon marginal attacks and switch to a defensive posture?

The correct choice indicates that command should abandon marginal attacks and switch to a defensive posture when a primary search gives an all clear. This is significant because the primary search is a critical phase in firefighting operations where firefighters search for potential victims in a structure. If the primary search concludes with an all clear, it implies that there are no individuals trapped inside, reducing the immediate threat to lives.

In such a situation, the objective shifts from aggressive interior firefighting – which involves risks to personnel and aims to control the fire at close quarters – to ensuring the safety of the firefighting team and the surrounding area. A defensive posture prioritizes protecting lives and property from further damage, considering that there’s no longer a risk to occupants. This transition is also informed by the recognition that further interior operations may not provide enough benefit to justify the risks involved when the presence of victims is no longer a concern.

The other options, such as the arrival of backup, establishing a strong water supply, or ensuring the building is secure, are important aspects of firefighting strategy but do not inherently necessitate a shift to a defensive stance in the same way that confirming an all clear does. The confirmation of no remaining civilians or potential victims allows for a more strategic and cautious approach