Which three statements are true about Source Specific Multicast？（）

• A、Is best suited for applications that are in the one-to-many category.
• B、SSM uses shortest path trees only.
• C、The use of SSM is recommended when there are many sources and it is desirable to keep the amount of mroute state in the routers in the network to a.
• D、There are no RPs to worry about.