How do postage rates vary by mail class?

The reason different services have specific costs based on weight, size, and delivery speed is rooted in the operational requirements and logistical considerations of postal services. For instance, first-class mail may charge higher rates for faster delivery, while standard mail services can be more economical for less time-sensitive items.

Weight affects cost because heavier packages require more resources to transport. Similarly, size plays a critical role, as larger items may need special handling, which incurs additional costs. Delivery speed is a major factor since expedited services generally cost more than standard delivery options due to the prioritized handling they require. This nuanced structure allows postal services to cater to various needs, giving customers a range of options depending on their urgency and budget constraints. Thus, the correct answer captures the complexity of how postage rates are established across different mail classes.