What service can you use to ensure a piece of mail is delivered on a specific date?

Priority Mail Express is the correct answer because it is the only USPS service that guarantees delivery on a specific date and time, including weekends and holidays. This service is designed for urgent and time-sensitive shipments, providing customers with a reliable option when they need to ensure that a package or piece of mail arrives precisely when it's needed.

In contrast, First-Class Mail is generally reliable and offers fast delivery, but it does not guarantee a specific delivery date. Standard Post and Media Mail also do not provide guarantees for delivery dates; they are more economical options for shipping but are subject to standard delivery times that are not fixed. Therefore, for anyone needing to ensure a specific delivery date, Priority Mail Express is the best choice.