Which of the following best describes a "school zone" speed limit?

A "school zone" speed limit is designed to ensure the safety of children as they enter and exit school premises. It typically involves a reduced speed limit during specific times, particularly when children are actively arriving at or leaving school, which can include before and after school hours as well as during certain events. This reduced speed is strategically implemented to minimize the risk of accidents in areas where children may unexpectedly cross the street or gather.

The other choices don't adequately capture the essence of a school zone speed limit. The speed limit in residential areas may be different and does not necessarily change for school zones. Although some jurisdictions may set a universal speed limit of 25 mph in school zones, this is not a universal standard and can vary based on local laws; hence, stating it as a fixed speed limit is not accurate. Finally, indicating that no limit applies contradicts the very purpose of a school zone, which is to impose a specific speed limit to improve safety.