In alphabet series, some alphabets are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.
_ cb _ ca _ bacb _ ca _ bac _ d
abca _ bcaab _ ca _ bbc _ a
_ bbca _ bcca _ ac _ a _ cb
a _ ca _ bc _ bcc _ bca
_ bca _ cca _ ca _ b _ c
_ abb _ _ bb _ a _ bbab _ ba