1. 

In the following question, a letter series is given. Some of the letters of the series are missing. This missing letters are given in same order as one of the four/five alternatives below the series. Find out the correct alternative.

ZYX__W__YZZ__XWWXY__
A. WXYZ
B. WYXZ
C. WXZY
D. XYZW

Answer: Option A

Explanation:

Pattern of the series as shown below

ZYXW/WXYZ/ZYXW/WXYZ => WXYZ

Hence, the missing letters are WXYZ.