Letter series ABC DEF GHI JKL – UGC NET Question

Each term consists of three consecutive letters taken in blocks: ABC (1–3), DEF (4–6), GHI (7–9) and JKL (10–12). The starting positions of the blocks are 1, 4, 7 and 10, increasing by 3. The next block must therefore start at position 13, giving the letters M, N and O. Hence MNO is the only group that follows the established block-wise progression.

Option A:
Option A is correct because it continues the pattern of non-overlapping three-letter blocks in alphabetical order. After JKL, the natural next block is MNO, covering positions 13–15. It respects both the length of each group and the sequential order of letters. Therefore MNO is the exact logical continuation.

Option B:
Option B, NOP, begins at N instead of M, which would start a block at position 14 rather than 13. This breaks the rule that the start of each block is 3 letters ahead of the previous one. Since it shifts the entire block by one extra letter, NOP does not fit the series.

Option C:
Option C, LMN, overlaps with JKL because L already appears as the last letter of JKL. The series is constructed from disjoint groups of three letters without repetition across block boundaries. Because LMN reuses L and disturbs the block structure, it is not acceptable.

Option D:
Option D, PQR, skips several letters after L and jumps to P, breaking the continuous alphabetical order. This disrupts the regular stepping of three consecutive letters. As a result, PQR fails to maintain the defining structure of the sequence.