题目内容：
Refer to the network of Layer 3 switches in the exhibit. The RPI Multi cast Server only multicasts to hosts connected to multilayer switches 5 and 6. The CMU Multicast Server multicasts to hosts on multilayer switches 1 - 6. Given the number of configuration steps involved, what is the most efficient way to configure the net work while meeting the requirements for multicast data flow? （）
A. Configure each switch with PIM sparse mode and a separate instance of PIM dense mode.Specify switch 1 as the root for the RPI Multicast Server. Specify switch 2 as the root for the CMU Multicast Server.
B. Configure each switch with PIM sparse mode and a separate instance of PIM dense mode. Leave each multicast server as the root of its own multicast tree.
C. Configure each switch with PIM sparse - dense mode. Configure switch 3 as a ren dezvous point for the RPI multicast stream.
D. Configure each switch with PIM sparse mode and a separate instance of PIM dense mode.Allow the switches to elect their own root for each multicast tree.
E. Configure each switch with PIM sparse mode.
F. Configure each switch with PIM dense mode.
参考答案：