Correct option is A
Given:
_QMRN_OTPU_VRWS_ TYU_
Let's check each option:
Option A: L S Q X Z

Follow alternate pattern 1st letter and 3rd letter...(+1) also 2nd and 4th letter...(+1).
Option B: K S N X W
K Q M R N S O T P U N V R W S X T Y U W
(Not a logical repeating pattern)
Option C: L R Q U Z
L Q M R N R O T P U Q V R W S U T Y U Z
(Not a logical repeating pattern)
Option D: K R N U W
K Q M R N R O T P U N V R W S U T Y U W
(Not a logical repeating pattern)
Thus, the correct option is: (a)