Which of the following is a valid IPv$6$ address format?

Question $23$ Answer

a$.$

$2001$:$8888$:EEEE:$1010$:$0000$:$0000$:$0000$:$0001$

b$.$

G$412$:AFFA:$2001$:$0000$:$0000$:$0000$:$0000$:$0001$

c$.$

$2010$:$2112$:$5440$:$1812$:$1867$

d$.$

$2001$::$8888$::$1$