In alphabet series, some alphabets are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.
abca _ bcaab _ aa _ caa _ c
abca _ bcaab _ ca _ bbc _ a
ccbab _ caa _ bccc _ a _
c _ ac _ aa _ aa _ bc _ bcc
ab _ aa _ bbb _ aaa _ bbba
ab _ aa _ caab _ c _ abb _ c