In alphabet series, some alphabets are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.
ccbab _ caa _ bccc _ a _
abca _ bcaab _ aa _ caa _ c
_ _ babbba _ a _ _
_ baa _ aab _ a _ a
aa _ ab _ _ aaa _ a
mnonopqopqrs _ _ _ _ _