Given:
A'(A'+B'),A=A+0 apply it to the first term of A
A'(A'+B')=(A+0)' (A'+B')
=>(A'. 0') (A'+B') [DEMORGAN'S THEOREM]
=>(A'. 1) (A'+B') [(A'. 1)= A' IDENTITY]
=>A'(A'+B') [ASSOCIATIVE LAW]
=>(A'.A')+B' [A'.A'=A' IDEMPOTENT LAW]
=>A'+B' [(A.B)'=A'+B' DEMORGAN THEOREM]
=> (A.B)' [CORRECT ME WHERE I HAVE GONE WRONG BECAUSE MY ANSWER IS NOT GIVEN IN THE OPTION [LINK FOR BOOLEAN RULES=http://www.electronics-tutorials.ws/boolean/bool_6.html ]