In alphabet series, some alphabets are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.
abb _ baa _ a _ bab _ aba
_ baa _ aab _ a _ a
ab _ bcbca _ _ c _ bab
_ aba _ cabc _ dcba _ bab _ a
c _ baa _ aca _ cacab _ acac _ bca
ba _ b _ aabb _ a _ _ a _ bb