Correct Answer: bddcb

Solution : Given:
b_cd_d_bcc_cdb_

To fill the series we have to divide the series – b_cd_/d_bcc/_cdb_
Let's check the options –
First option: dbbbc; b d cd b /d b bcc/ b cdb c (No pattern has been found.)
Second option: bddcb; b b cd d /d d bcc/ c cdb b (The first two and the last two letters are the same in each set.)
Third option: dccbd; b d cd c /d c bcc/ b cdb d (No pattern has been found.)
Fourth option: bcccb; b b cd c /d c bcc/ c cdb b (No pattern has been found.)

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