1.  P5QR, P4QS, P3QT, _____, P1QV

A. PQW
B. PQV2
C. P2QU
D. PQ3U

Answer: Option C

Explanation:

The first two letters, PQ, are static. The third letter is in alphabetical order, beginning with R. The number series is in descending order beginning with 5.