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.

a__bc__a__bcda__ccd__bcd__
A. abddbd
B. acbdbb
C. adbbad
D. adbcad

Answer: Option C

Explanation:

Pattern of the series as shown below

aabcd/abbcd/abccd/abcdd => adbbad

Hence, the missing letters are adbbad.