Q43,paper 3, J12. The regular expression for the following DFA is

Options
(A) ab*(b + aa*b)*
(B) a*b(b + aa*b)*
(C) a*b(b* + aa*b)
(D) a*b(b * + aa*b)*
Answer (D)
Explanation
From the DFA find out string of length 1 that is {b} String of length 2 is {ab, bb} String of length 3 is {aab, abb, bab, bbb}. String of length 4 is {babb----} Now seeing the option re of option A fails to realize {b} hence option A is discarded.{ab,bb} can be realized by by option B,C,D. string of length3 ,aab can be realized by option B,C,D. String abb can be realized by option B,C,D. string bab can be realized by option B,C,D.check for string of length 4.