A letter series is given below in which some letters are missing. Select the option that gives the letters that can fill these blanks in that order.

cd_cc_ca_dc_cbc_c_cc_bca

cbccadc

The given series is cd_cc_ca / _dc_cbc_ / c_cc_bca

On observing it closely, we can complete the series as: cdcccbca / cdcccbca / cdcccbca

So, cbccadc