BZX, DXT, FVP, ?

Concept

In a letter-series item, treat each letter by its alphabet position (A=1 ... Z=26). Look for a constant step applied separately to each position within the triplet across consecutive terms, and confirm the same step holds for every given term before extending it to the missing one.

Application

Convert each triplet to numbers: BZX -> (2, 26, 24); DXT -> (4, 24, 20); FVP -> (6, 22, 16). The first position rises by a constant +2 (2, 4, 6); the second falls by a constant -2 (26, 24, 22); the third falls by a constant -4 (24, 20, 16), consistent with third = second - first at every step (26-2=24, 24-4=20, 22-6=16). Extending each step: first letter 6+2=8 -> H; second letter 22-2=20 -> T; third letter 16-4=12 -> L (equivalently 20-8=12). The next term is HTL.

Cross-check

Cross-checking independently via the second-minus-first identity: 20-8=12=L, which matches the -4 step obtained directly from the third-letter sequence (24, 20, 16, -> 12). Both methods agree, confirming HTL.