Users report that IPTV has a long time delay when changing channels. In order to improve the experience of channel switching for general users, the program pre-join function can be configured. Which of the following configurations can realize program pre-join?
A . huawei (config) mlti cast-vlan x
huawei (config-mlan x) igmp program static ip 224.x..x enable
B . Huawei (config) #igmp program static ip 224.x.x.x anable
C . huawei(config)#ml ticast-vlan x
Huawei (config-mwlan x) #igmp program add ip 224.x.x.x prejoin enable
D . huawei （ config ） #igmp program add ip 224.x.x.x prejoin an able
Answer: C