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

fe$00$::b$491$:cf$79$:p$493$:$23$ff

$2001$:$0$:$49$e$6$:$39$ff:$8$cf$5$:$6812$:ef$56$

$2001$:$0$:$44$ef$68$:$23$eb:$99$fe:$72$bec$6$:ea$5$f

fe$00$::c$955$:c$944$:acdd:$3$fcb