Reverse alphabet triplets puzzle: fill the blank in QPO, NML, KJI, ____, EDC by continuing groups of three consecutive letters in descending order with a −3 shift on the starting letter.

Each term is a three-letter block in strict reverse order; the block's first letter descends by 3 between terms.

• Blocks: QPO (Q→P→O), NML (N→M→L), KJI (K→J→I), ? , EDC (E→D→C).
• Start letters: Q → N → K → H → E (−3 each step).