Correct Answer: bacc

Solution : Given:
ac_c_cb_acbcacbca_bc

To fill the series we have to divide the series→ ac_c / _cb_ / acbc / acbc / a_bc
Let's check each option –
First option: abbb; ac a c / b cb b / acbc / acbc / a b bc (No repeated pattern has been found.)
Second option: bacc; ac b c / a cb c / acbc / acbc / a c bc (acbc is repeated in the series.)
Third option: babc; ac b c / a cb b / acbc / acbc / a c bc (No repeated pattern has been found.)
Fourth option: bbcc; ac b c / b cb c / acbc / acbc / a c bc (No repeated pattern has been found.)

So, the series becomes→acbcacbcacbcacbcacbc. Hence, the second option is correct.