Select the combination of letters that when sequentially placed in the blanks of the given series will make the series logically complete.
_XYZU_UUSR_PQOM_

 In the given letter series, some of the letters are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.

abab c_cd a_ab cd_d ab_b cdc_

​In the following series, some of the letters are missing, which are given in that order as one of the alternatives. Choose the correct option.
zy_wwx_zzyx_w_yzz_xw

In the following question, which one set of letters and numbers, when sequentially placed in the blanks of the given letter-number series, will complete it logically?
u _ v _ w 35 x 40 y 45 z 50

Observe the following incomplete letter sequence carefully:
 a a _ b c c _ a b b c _ a a b b _ c
A specific pattern governs the order and repetition of the letters. Choose the option that best fills the blanks (in order) to complete the sequence logically and symmetrically. ​​​​