问题：

[单选] What does a router do?（）

A . Stores data on the network and connects the local-area network (LAN) to the wide-area network (WAN)
B . Routes traffic down alternative paths and connects the local-area network (LAN) to the wide- area network (WAN)
C . Broadcasts data to all devices that are connected to it across the local-area network (LAN) and wide-area network (WAN)
D . Reads Media Access Control (MAC) addresses to forward messages to the correct location and connects the local-area network (LAN) to the wide-area network (WAN)