ITN $($Version $7\mathrm{.}00)-$ IP Addressing Exam

$30$ Which is the compressed format of the IPv$6$ address $2001$:$0$db$8$:$0000$:$0000$:$0000$:a$0$b$0$:$0008$:$0001?$

$2001$:db$8$::ab$8$:$1$:$0$:$1000$

$2001$:db$80$:$0$:$1$::$80$:$1$

$2001$:db$8$:$0$:$1$:$8$:$1$

$2001$:db$8$::a$0$b$0$:$8$:$1$