Final answer:
In multicast routing, routers create a shared path tree for each group, optimizing the delivery of data to multiple receivers.
Step-by-step explanation:
In multicast routing, each involved router needs to construct a shared path tree for each group. Multicast routing is used when the same data needs to be delivered to multiple receivers. Instead of creating individual paths for each receiver, a shared tree allows routers to use the same path to deliver this data to all group members, reducing the overall network load and improving efficiency. This shared tree is also known as a rendezvous point tree, where the rendezvous point acts as the root of the tree through which all multicast traffic for a group is forwarded.