For which two reasons does music on hold fail to play?

A.	The DRAM is corrupted on the Cisco IOS router.
B.	Unicast music on hold is configured and the IP addressing mode is set to IPv4 Only.
C.	A SIP trunk is configured between the phone and the music on hold server.
D.	iPv4 addressing is in use.
E.	Multicast music on hold is configured and the IP addressing mode is set to IPv6 Only.
F.	Analog lines are terminated into the voice gateway.