Correct Answer: acbcb

Solution : Given:
c_bba_cab_ac_ab_ac

To fill the series we have to divide the series – c_b/ba_/cab/_ac/_ab/_ac
Let's check each option:
First option: babcc; c b b/ba a /cab/ b ac/ c ab/ c ac; (No pattern has been found.)
Second option: bcacb; c b b/ba c /cab/ a ac/ c ab/ b ac; (No pattern has been found.)
Third option: acbcb; c a b/ba c /cab/ b ac/ c ab/ b ac; (cab, bac has been repeated.)
Fourth option: abcbc; c a b/ba b /cab/ c ac/ b ab/ c ac; (No pattern has been found.)

So, the series becomes→cabbaccabbaccabbac. Hence, the third option is correct.