What are the three different modes of PIM?

The three different modes of Protocol Independent Multicast (PIM) are indeed dense mode, sparse mode, and sparse-dense mode.

Dense mode is used in scenarios where there are many receivers located close to the multicast source. In this mode, multicast traffic is initially flooded to all links and then pruned from links where there are no receivers. This approach is efficient in environments with high-density multicast receiver populations.

Sparse mode, on the other hand, is designed for environments where receivers are dispersed across a wide area. In this mode, multicast traffic is only sent to the networks that actively require it. It involves the use of a shared tree (Rendezvous Point) to establish a more efficient and organized way of managing multicast group memberships and routing.

The term "sparse-dense mode" refers to a PIM mode that allows the use of both dense and sparse modes within the same network. This can be particularly useful in hybrid networks where some segments may require dense mode while others require sparse mode, allowing for greater flexibility in multicast routing.

The other options do not represent the established modes of PIM correctly, making this combination the accurate choice for identifying the different modes of Protocol Independent Multicast.