Correct Answer: BCCB

Solution : Given:
B _ CCABB _ CABBC _AB_ CCA

To fill the series we have to divide the series – B _ CCA/BB _ CA/BBC _A/B_ CCA
Let's check the options –
First option: BCBC; B B CCA/BB C CA/BBC B A/B C CCA (No pattern has been found.)
Second option: BBBC; B B CCA/BB B CA/BBC B A/B C CCA (No pattern has been found.)
Third option: BCCB; B B CCA/BB C CA/BBC C A/B B CCA (BBCCA is repeated in the series.)
Fourth option: BBCC; B B CCA/BB B CA/BBC C A/B C CCA (No pattern has been found.)

So, the series becomes→B B CCABB C CABBC C AB B CCA. Hence, the third option is correct.