Which of the following options can improve the service experience of multicast users when switching channels (shorter switching time)?

Which of the following options can improve the service experience of multicast users when switching channels (shorter switching time)?
A . When adding a multicast program, prohibit the prejoin function
B . Enable fast leave function when adding multicast users
C . When adding a multicast user, enable the preview function
D . Use a low-value multicast address

Answer: C