In relation to MPLS Multicast VPN， which three statements about multicast distribution （MDT） groups aretrue？ （）

A.Default MDT groups are used for PIM control traffic， low-bandwidth sources， and flooding of sparse mode traffic.
B.MDTs are built in customer networks
C.Data MDT groups are used for high-bandwidth sources to reduce replication to uninterested PEs.
D.MDTs are built in provider networks
E.The number of MDTs depends on PIM modes of MDT groups.