Letter series ABO BCP CDQ DER – UGC NET Question

In this series, each position in the triplets increases by one letter from term to term. First letters: A, B, C, D move to E; second letters: B, C, D, E move to F; third letters: O, P, Q, R move to S. Combining these gives the next group as EFS. Thus EFS preserves the simultaneous +1 shift in all three positions.

Option A:
Option A, EFT, has the correct first two letters E and F but changes the third letter to T instead of S. The third letters should increase in order O, P, Q, R, S, not jump to T. Because it breaks the regular one-step progression in the third position, EFT is not correct.

Option B:
Option B, EFR, keeps E and F but reuses R as the third letter. The third position should move from R to S, not stay at the same letter. Repetition of R violates the strictly increasing pattern in the last position, so EFR cannot be the right continuation.

Option C:
Option C is correct because E, F and S are each exactly one step ahead of D, E and R respectively. It respects the coordinated forward shift in all three positions, which is the hallmark of this series. Therefore EFS is the only triplet that fits the established pattern.

Option D:
Option D, EGT, alters both the second and third positions by more than one step. The series does not support unequal or larger jumps in any position. As it disrupts the neat parallel movement of all three letters, EGT is not a valid next term.