Correct Answer: EISIEUD

Solution : Given:
FIR_DF_ _EDF_T_DFI_E_

To fill the series, we have to divide the series – FIR_D / F_ _ED / F_T_D / FI_E_
Let's check each option –
First option: EISIEUD; FIR E D / F IS ED / F I T E D / FI U E D (FIED is repeated in the series and the third letter of each part are in sequential alphabetical order.)
Second option: EGSJEUE; FIR E D / F G S ED / F J T E D / FI U E E (No repeated pattern has been found.)
Third option: EHSIEUD; FIR E D / F HS ED / F I T E D / FI U E D (No repeated pattern has been found.)
Fourth option: EISIEUE; FIR E D / F I S ED / F I T E D / FI U E E (No repeated pattern has been found.)

So, the series becomes→FIREDFISEDFITEDFIUED. Hence, the first option is correct.