1. 

Which of the following terms follows the trend of the given list?

YXXXXXX, YYXXXXX, YYYXXXX, YYYYXXX, YYYYYXX, _____

A. XXXXXXX
B. YXXXXXX
C. YYYYYYX
D. YYXXXXX

Answer: Option C

Explanation:

Pattern of the series as shown below

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

Hence, the missing term is YYYYYYX.