Correct Answer: DCED

Solution : Given:
CD_E_DD_CD_E

To fill the series we have to divide the series – CD_E / _DD_ / CD_E
Let's check each option –
First option: CDCD; CD C E / D DD C / CD E E (No repeated pattern has been found)
Second option: DCCC; CD D E / C DDC / CD C E (No repeated pattern has been found)
Third option: DCED; CD D E / C DD E / CD D E (CDDE is repeated in the series)
Fourth option : DDDC; CD D E / D DD D / CD C E (No repeated pattern has been found)

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