In English alphabet, the number of letters skipped in between adjacent letters…

Concept: In an alphabet letter series, first assign each letter its position in the alphabet (A = 1, B = 2, ..., Z = 26). Between any two consecutive letters in the series, the number of letters skipped equals (difference in position minus 1). A series that "decreases by one" must produce a sequence of skip counts that falls by exactly 1 at every step, for example 5, 4, 3, 2.

Application: For DJOSV, the letters occupy positions D = 4, J = 10, O = 15, S = 19, V = 22. Computing the skipped letters at each step:

1. D to J: position difference 10 - 4 = 6, so 6 - 1 = 5 letters are skipped (E, F, G, H, I).

2. J to O: position difference 15 - 10 = 5, so 4 letters are skipped (K, L, M, N).

3. O to S: position difference 19 - 15 = 4, so 3 letters are skipped (P, Q, R).

4. S to V: position difference 22 - 19 = 3, so 2 letters are skipped (T, U).

The skip counts form the sequence 5, 4, 3, 2 - a strict decrease of exactly one letter at every step, so DJOSV follows the rule completely.

Cross-check: Applying the same method to a series such as DJOTV gives skip counts 5, 4, 4, 1 - the third gap repeats the previous count instead of continuing to fall by one, so that series breaks the rule. This confirms DJOSV is the series that satisfies the given condition throughout.