Refer to the exhibit. All multilayer switches are running PIM dense mode. Recipient A and Recipient B are sending IGMPv2 joi n messages to their respective multilayer switches. Which statement is true?（）

• A、The Multicast Server is the root of the multicast tree. Switches 1, 3, 4, and 5 will participate in the multicast tree once pruning has taken place.
• B、The Multicast Serv er is the root of the multicast tree. Switches 4 and 5 will participate in the multicast tree once pruning has taken place.
• C、Switch 3 is the root of the multicast tree. Switches 3,4, and 5 will participate in the multicast tree once pruning has taken  place.
• D、Switch 3 is the root of the multicast tree. Switches 1,3,4, and 5 will participate in the multicast tree once pruning has taken place.
• E、Switch 1 is the root of the multicast tree. Switches 1,4, and 5 will participate in the multicast tree once pruning has taken place.
• F、Switch 1 is the root of the multicast tree. Switches 1,3,4, and 5 will participate in the multicast tree once pruning has taken place.