WYB, XUD, YQF, ...

Solution: Analyze each letter position separately.

• First letters: W → X → Y (each step +1), so the next first letter is Z.

• Second letters: Y → U → Q (each step −4), so the next second letter is M.

• Third letters: B → D → F (each step +2), so the next third letter is H.

Combine the results: ZMH