In each of the following questions there is a series of letters with one term…

Concept: In a letter-series puzzle built from multi-letter terms, each character position (first, second, third, and so on) advances independently through the alphabet following its own fixed step from one term to the next. To find a missing term, isolate the letters occupying each position across the given terms, identify the alphabetical rule for that position alone, and then apply it to generate the corresponding letter of the missing term.

Application: The given series is KPA, LQB, MRC, NSD. Track each of the three positions separately across these four terms:

1. First-position letters: K, L, M, N — each letter advances one step ahead of the previous one (+1 in the alphabet). Continuing this run gives the next first-position letter, O.

2. Second-position letters: P, Q, R, S — these also advance by one step each time. Continuing this run gives the next second-position letter, T.

3. Third-position letters: A, B, C, D — these also advance by one step each time. Continuing this run gives the next third-position letter, E.

Combining the three positions in order gives the missing term: O, T, E, which is written as OTE.

Cross-check: Re-reading each position's full run independently — K, L, M, N, O; P, Q, R, S, T; A, B, C, D, E — each is a clean, unbroken consecutive alphabetical sequence, confirming OTE as the missing term.