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.

LU__TUPLUBTU__LUBT__P__UBTUP
A. BPUL
B. LBPU
C. PBUL
D. BUPL

Answer: Option A

Explanation:

Pattern of the series as shown below

LUB/TUP/LUB/TUP/LUB/TUP/LUB/TUP => BPUL

The series is made of repetition of patterns 'LUB' and 'TUP' alternatively.

Hence, the missing letters are BPUL.