Select the letter-cluster that can replace the question mark (?) in the following series.

eBd, hXi, kTn, nPs, ?

qLx

Explanation:

eBd, hXi, kTn, nPs, ?

The logic followed here is :

e → (+3) → h → (+3) → k → (+3) → n → (+3) → q

B → (-4) → X → (-4) → T → (-4) → P → (-4) → L

d → (+5) → i → (+5) → n → (+5) → s → (+5) → x

So, the letter-cluster that replaces the (?) to complete the series is "qLx"