Which of the following options is a potential hazard when using ladders?

Slippery surfaces represent a significant potential hazard when using ladders. When a ladder is set up on a slick or unstable surface, such as wet ground, ice, or a polished floor, the risk of slipping increases dramatically. This can lead to loss of balance while climbing or descending the ladder, which could result in falls and serious injuries. Ensuring that the ladder is placed on a stable, dry, and even surface is essential for maintaining safety during use.

In contrast, overlapping rungs, while they might affect the usability or design of a ladder, do not necessarily represent a direct hazard like slippery surfaces do. Stable footing and adjustable height, on the other hand, are features that contribute to the safety and functionality of a ladder when used correctly. It is critical for users to always be aware of their surroundings, particularly with regard to the surface on which the ladder is positioned, to prevent accidents.