Which device handles the translation between internal IP addresses and external IP addresses in a network?

The correct choice is the router because it plays a key role in managing network traffic and facilitating communication between different networks. Specifically, routers use a process known as Network Address Translation (NAT) to convert private, internal IP addresses to public, external IP addresses when data packets leave a local network. This is essential for communicating over the internet, as internal IP addresses are not routable on public networks.

In contrast, other devices such as switches, access points, and hubs serve different functions. A switch operates at the data link layer and primarily directs data packets within the same network by using MAC addresses. An access point provides connectivity for devices to join the network wirelessly, while a hub is a basic networking device that connects multiple Ethernet devices, signaling all nodes in the network without filtering or directing traffic effectively. Each of these devices lacks the necessary functionality to perform address translation, which is why the router is the correct answer.