Select the combination of letters that when sequentially placed in the gaps of the given letter series will complete the series. s_ft_eq_rf_ae_sr_ta_q

tstsqfe srtsqfe rastqfe ratsqfe

rastqfe

After dividing it into 3 groups of 7 each and comparing the corresponding term we, get srftaeq as the repetitive term. srftaeq / srftaeq / srftaeq So, the code will be rastqfe