During which hours is the speed limit tab in effect under a school zone sign?

The speed limit tab under a school zone sign is specifically designed to enhance the safety of children during the hours when they are most likely to be arriving at or departing from school. The typical enforcement hours from 8 am to 5 pm align with the start and end of the school day, making it crucial for drivers to reduce their speed during these times. This period effectively covers the times when students are walking to or from school, ensuring added protection during peak traffic times in school zones.

The other options, while they reflect different ranges of time, do not accurately capture the designated hours that authorities want drivers to be cautious in school zones. For example, having a speed limit in effect dawn to dusk might be overly broad and not aligned with actual school hours, and specific options like 6 am to 9 am wouldn't encompass the full school day.