What is the maximum length to extend an extension ladder?

An extension ladder is designed to safely extend to a certain maximum height, which corresponds to its construction and stability characteristics. In this case, the correct option indicates that an extension ladder can safely extend up to 55 feet. This limitation is important to ensure the ladder maintains its structural integrity while in use and provides proper stability for the user.

Ladders are subject to safety standards and design specifications that dictate their maximum extension lengths based on user safety. Extending beyond this limit may compromise the ladder's stability, significantly increasing the risk of accidents or falls. Understanding and adhering to these maximum lengths is critical for safe ladder operation and effective work practices.

The other options, while they represent possible lengths for some ladders, do not reflect the appropriate maximum for an extension ladder as defined by safety guidelines and engineering principles. Thus, sticking to the maximum acceptable length ensures professional safety standards are met.