Three-letter blocks descending by one – UGC NET Question

The series consists of overlapping three letter blocks in forward order, while the starting letter moves backward by one each time. Starting letters S, R, Q and P occupy positions 19, 18, 17 and 16, decreasing by 1. The next starting letter must therefore be O at position 15, leading to the block OPQ. This group keeps the internal order and the backward movement of the starting position.

Option A:
Option A, ONP, uses the correct starting letter O but arranges the remaining letters out of consecutive order. The letters N and P do not appear in correct sequence following O. Because each group in the series is strictly built from consecutive letters in increasing order, ONP is not acceptable.

Option B:
Option B, PQR, repeats the last given group instead of moving to the next starting letter. The pattern does not involve repetition; it consistently shifts the starting point backward along the alphabet. For that reason, PQR cannot be the next term.

Option C:
Option C, NOP, starts at N, which is two positions before P rather than one. Although NOP is a consecutive block, it does not correctly mirror the one step backward movement seen in the starting letters. Therefore NOP breaks the established positional rule.

Option D:
Option D is correct because OPQ begins with O, exactly one step before P, and continues with P and Q in order. It maintains the overlapping structure and the uniform backward shift of the starting letter. This agreement with both the structure and movement of the series makes OPQ the logical continuation.