Which two multicast protocol statements are true？ （Choose two.）  （）

• A、 Dense mode multicast requires explicit join messages from their members.
• B、 Dense mode multicast uses a push model to flood traffic throughout the network and then prunes the  unwanted traffic.
• C、 Sparse mode multicast uses a pull model to send multicast traffic to where it is requested.  
• D、 Sparse mode uses reverse path forwarding （RPF） to prune off redundant flows.
• E、 The primary use of sparse mode multicast is for test labs and router performance testing.