Listen to exam instructions

Consider the following IPv$6$ address:

FE$80$:$0000$:$0000$:$0055$:$0000$:$0000$:$000$A:AB$00$

Which of the following are valid shortened forms of this address? $($Select two.$)$

answer

FE$80$:$0000$:$0000$:$0055$::$000$A:AB$00$

FE$80$::$0055$::$000$A:AB

FE$80$::$55$::A:AB

FE$80$::$55$::A:AB$00$

FE$80$::$55$:$0000$:$0000$:A:AB$00$