Which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?  _ Y _ X_ Z X _ Z X _ _ X Y _

The original series is as follows: _ Y _ X_ Z X _ Z X _ _ X Y _ On observing the series we are unable to infer any pattern. In such questions, it’s more prudent to take help of the options. On checking each option, we find that a pattern indeed emerges when the letters given under option (B) are used to complete the series. The completed series has been represented below:   X Y Z / X Y Z / X Y Z /X YZ /X Y Z We can see that the pattern ‘XYZ’ is being repeated in the series given above. Hence, option (2) is the correct answer