What type of switch is designed to prevent sagging steps in elevators?

The correct answer, which specifies a step level switch, highlights its crucial role in maintaining the proper alignment of the escalator steps with the landing. This switch is designed to detect whether the escalator steps are in a level position when they arrive at the landing, which is essential for user safety and comfort. If the steps are sagging or not aligned properly, the switch will trigger safety mechanisms to halt the escalator, preventing potential accidents for passengers.

In contrast, gravity switches typically respond to changes in weight or load, limit switches are used to detect the maximum or minimum positions of moving parts, and pressure switches activate depending on the pressure of gases or liquids. While these may be essential in their respective functions, they do not specifically address the issue of escalator step alignment, which is the focus of the question. Thus, understanding the function of a step level switch clarifies its importance in keeping escalators safe and operational for users.