以下哪一项代表一个有效的IPv6地址?
A 2001:cf8:5403:3000:b5ea:eadd:679f:30f5
B 2001:cf8:5403:3000:b5ea:eadd:679f:30f5:af54
C 2001:cf8:5403:3000:b5ea:eadd
D 2001:cf8:5403:3000:b5ea:eadd:679f
A 2001:cf8:5403:3000:b5ea:eadd:679f:30f5
B 2001:cf8:5403:3000:b5ea:eadd:679f:30f5:af54
C 2001:cf8:5403:3000:b5ea:eadd
D 2001:cf8:5403:3000:b5ea:eadd:679f