give the regular expression of this DFA text please explain your process and answer

$\{0,1,2\}$

$\{$a$,$b$,$c$,$d$\}$

a

$\{$b$,$d$\}$

$($a$,0)->$c

$($a$,1)->$b

$($a$,2)->0$

$($b$,0)->$c

$($b$,1)->$a

$($b$,2)->$c

$($c$,0)->$d

$($c$,1)->$d

$($c$,2)->$c

$($d$,0)->0$

$($d$,1)->$d

$($d$,2)->$b