What service should be used for mail requiring signature confirmation?

The correct choice emphasizes the importance of certified mail, which is specifically designed for items that require a signature confirmation upon delivery. This service is ideal for sending important documents or items, as it provides the sender with proof of delivery. When a recipient signs for the mail, a record is created, which serves as verification that the item was indeed received by the intended person.

In contrast, the other services listed do not inherently offer this feature. Standard Mail is primarily used for bulk or advertising mail and lacks tracking or signature options. Priority Mail provides faster delivery but does not guarantee a signature confirmation unless combined with specific services. First-Class Mail, while it allows for tracking, does not automatically include signature confirmation. Therefore, certified mail stands out as the most reliable option for those needing a documented assurance of delivery through a signature.