1. 

letters are arranged in a particular order with some criterion. Find out the right one to fill in the blank.

A, CD, GHI, _____, UVWXY

A. LMNO
B. NOPQ
C. KLMN
D. MNOP

Answer: Option D

Explanation:

Pattern of the series as shown below

letter-and-symbol-series-logical-reasoning-introduction---letter-and symbol-series-problems

The number of letter in the terms of the series increases by one at each step.

Each, term consists of consecutive letters in order.

Hence, the missing term is MNOP.