What type of construction feature mainly ensures safety for people with disabilities when navigating changes in level?

The correct answer focuses on the construction feature that ensures safety for individuals with disabilities when navigating changes in level, specifically highlighting dropped curbs. Dropped curbs provide a gradual transition from sidewalks to streets, eliminating abrupt changes in height that could pose a hazard. They are designed to facilitate wheelchair access, making it easier for individuals with mobility impairments to move from one surface to another without the risk of stumbling or falling.

In contrast, other options play different roles in accessibility but do not specifically address the direct need for safe navigation over level changes in the same way that dropped curbs do. Handrails enhance stability but do not assist with elevation changes themselves, while elevators are significant for moving between levels in buildings but are not relevant in the context of external navigational features. Ramps are also important for providing level transitions, yet dropped curbs serve a unique purpose at street intersections, making them particularly critical for safety in urban environments.

Recognizing this distinction helps clarify why dropped curbs are fundamentally aligned with the need to assist individuals with disabilities in safely navigating changes in level.