Which mailing service is used for items that weigh less than 13 ounces?

The correct choice is First Class Mail because this service is specifically designed for items weighing less than 13 ounces. First Class Mail offers reliable delivery for letters, postcards, and small packages, making it an ideal option for lightweight items. It provides a balance of speed and affordability, with typically faster delivery times compared to other services.

In contrast, while Priority Mail and Parcel Post can handle heavier weights, they are not limited to items under 13 ounces. Priority Mail is geared towards faster delivery of heavier parcels, typically above that weight limit. Media Mail, on the other hand, is a cost-effective option for shipping educational materials, but it comes with specific restrictions and does not apply to general mail items like letters or non-media packages. Thus, for items under 13 ounces, First Class Mail is the most appropriate choice.