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.

s__nx__mnx__mn__sm__x
A. mssxn
B. smnxx
C. nmxxn
D. nxyms

Answer: Option A

Explanation:

Pattern of the series as shown below

smnx/smnx/smnx/smnx => mssxn

Hence, the missing letters are mssxn.