What additional ladder must fire pumpers carry alongside a straight ladder and an extension ladder?

The correct choice in this scenario is the attic ladder. Fire pumpers are typically required to carry a variety of ladders to ensure they are equipped for different firefighting scenarios. An attic ladder is particularly useful in residential firefighting operations, where access to attics can be crucial for ventilation purposes and to locate hidden fires.

Attic ladders generally are compact and designed to be easily deployed in tight spaces, making them ideal for entering small openings, such as those found in residential ceilings leading to attic areas. Firefighters often encounter situations where they need to quickly access these spaces to check for hidden fire spreads that may not be visible from the main level of a structure.

The other types of ladders mentioned, like folding, roof, and wall ladders, may serve specific purposes but are not always standard or necessary for fire pumpers. For example, a roof ladder is designed specifically for use on roofs to provide stability and support. While useful, it is not as universally necessary as the attic ladder for the different types of incidents firefighters may address.