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.

bc__bca__cab__ab__a__ca

A. abcab
B. cabac
C. abccb
D. cabca

Answer: Option C

Explanation:

Pattern of the series as shown below

bca/bca/bca/bca/bca/bca => abccb

bc/abc/abc/abc/abc/abc/a => abccb

Hence, the missing letters are abccb.