Question $3(20$ points$).$ Given a relation R $($A$,$ B$,$ C$,$ D$).$ Answer the following questions

with the given set of FDs: $(1)$ identify candidate keys and $(2)$ state the strongest normal

form that $R$ satisfies $($e$.$g$.,1NF,2NF,3NF,$ or $BCNF)$

$($a$)$ FDs: $AB,AC,BCD$

$($b$)$ FDs: $ABCD,CDAB$

$($c$)$ FDs: $ADB,BDC$

$($d$)$ FDs: $ABC,BCD,CDA$

$($e$)$ FDs: $AB,BC,CD,DA$

Please give me correct step by step answer