Select the letter-cluster that can replace the question mark (?) in the following series. TXB, QWE, NVH, KUK, ?

HTN ITM JTM HSN

HTN

Explanation: TXB, QWE, NVH, KUK, ? The logic followed here is : T → (-3) → Q → (-3) → N → (-3) → K → (-3) → H X → (-1) → W → (-1) → V → (-1) → U → (-1) → T  B → (+3) → E → (+3) → H → (+3) → K → (+3) → N   So, the letter-cluster that replaces the (?) to complete the series is "HTN'