Identify the four valid IPv$6$ addresses. $($Choose four$)$

a$.2000$::

b$.2002$:c$0$a$8$:$101$::$42$

c$.$ ::

d$.2001$:$3452$:$4952$:$2837$::

e$.2003$:dead:beef:$4$dad:$23$:$46$:bb:$101$

f$.$ ::$192$:$168$:$0$:$1$