What items can be mailed under First Class Mail?

The correct answer is that First Class Mail can include letters, postcards, flats, and small packages. First Class Mail is designed for a variety of personal and business correspondence and is one of the fastest mailing options available.

This mailing service allows for the sending of standard-sized letters and postcards, as well as "flats," which are larger than letters but smaller than packages. Additionally, it includes small packages, making it versatile for both individual and commercial use. This wide range of acceptable items is a key feature of First Class Mail, enabling customers to use this service for different types of mail while ensuring quick delivery.

The other options fail to encompass the full range of items that can be mailed under this service. They either limit the types of allowed mail or impose weight restrictions that are not applicable to First Class Mail, which accommodates packages that are typically up to 13 ounces. Thus, the comprehensiveness of First Class Mail in including various forms of correspondence and small parcels makes it a preferred option for timely and efficient mailing.