check this one
I think it should be 6.
you didn't show transition on input a from final state..you have to make one more non final state.
if we take 1 more state, then minimum generated string of dfa is abbb
but according to question minimum generted string is abb
See this dfa-
It accepts abb.
yes nice one :)
@Verma Ashish yes I did a mistake, and not it is correct ..thanks