The proper length of a ladder to reach a second story window should be _______________.

To determine the proper length of a ladder to safely reach a second story window, it's important to consider the height of typical two-story structures. In residential buildings, the standard height for a second story generally ranges from 16 to 22 feet, accounting for variations in ceiling heights and the overall design of the structure.

Ladders that are 20 to 28 feet long provide the necessary reach while also allowing for safe positioning and angling of the ladder against the building. This range offers flexibility that can accommodate a variety of building designs and distances from the window edge. Using a ladder that is too short can compromise safety and accessibility, making the 20 to 28-foot ladder an optimal choice for fire and rescue operations involving second story windows.

The other options suggest lengths that would either be insufficient or excessively long, which can lead to difficulties in placement and stability during rescue efforts. Thus, the selected range effectively ensures that firefighters can safely and efficiently access windows on the second floor.