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.

ab__d__ __b__dm__ __x__ __
A. xmaxabda
B. xmaxabdm
C. mxaxabdm
D. mxaxbadm

Answer: Option B

Explanation:

Pattern of the series as shown below

Here, repeated pattern is 'abxdm'.

Now, abxdm/abxdm/abxdm => xmaxabdm

Hence, the missing letters are xmaxabdm.