What do the variables a and b refer to$,$ respectively, after the following code executes?

lst $=$ red fish blue frog egg.split$()$

it$1=$ iter$($lst$)$

it$2=$ iter$($lst$)$

next$($it$1),$ next$($it$2),$ next$($it$2)$

a$,$ b $=$ next$($it$1),$ next$($it$2)$

$($a$)$ frog and egg

$($b$)$ blue and egg

$($c$)$ red and frog

$($d$)$ fish and blue