What is the identifying feature of an IPv6 multicast address?

What is the identifying feature of an IPv6 multicast address?
A . The hexadecimal value FFFF appears as the first four characters of the address, followed by an arbitrary value.
B . The hexadecimal value FF appears as the first two characters of the address, followed by an arbitrary value.
C . The binary value 1111 appears as the first four characters of the address, followed by an arbitrary value.
D . The binary value 11 appears as the first two characters of the address, followed by an arbitrary value.

Answer: B