Which of the following holidays is not mentioned as a closing day for the driver license offices?

The selection of Earth Day as the holiday not mentioned as a closing day for driver license offices is accurate because it is not a federal holiday and typically does not warrant closures like the other options. Labor Day, Thanksgiving Day, and Christmas Eve are all widely recognized holidays that may involve office closures, as they are observed nationally and often have established protocols for businesses and government offices to operate. Given that Earth Day, while recognized for its environmental significance, is not part of the federal holiday calendar, it's less likely to be treated as a day off for state offices, including those that handle driver licenses. This distinction makes Earth Day the correct answer in this context.