what could be the cause of the problem?

Refer to the exhibit. IP multicast for group address 224.1.1.1 has been enabled on all routers
in the network. Hosts on Network A receive the multicast traffic. However, hosts on Network
B do not. On the basis of outputs provided, what could be the cause of the problem?

A.
Because of RPF failure, Router R2 does not forward multicast packets to Network B.

B.
The multicast packets are sourced from a server with an unspecified IP address.

C.
Router R2 does not see the upstream router R1 as a PIM neighbor.

D.
Router R2 does not have an RP configured on the multicast network.

Explanation:
Multicast routing uses a mechanism called Reverse Path Forwarding (RPF) to prevent
forwarding loops and to ensure the shortest path from the source to the receivers. If there is
RPF failure, the router does not forward the multicast packets to neighbor.