Four letter-clusters have been given, out of which three are alike in some manner and one is different. Select the letter-cluster that is different.

BEHK QTWZ XADG NPSV

NPSV

BEHK ⇒ B →(+3)→E →(+3) → H →(+3)→K QTWZ ⇒ Q →(+3)→T →(+3) → W →(+3)→Z XADG ⇒ X →(+3)→A→(+3) →D →(+3)→G NPSV ⇒ N→(+2) → P→(+3) → S →(+3)→V (ODD)