Which of the following letter-clusters will replace the question mark (?) in the given series to make it logically complete?

JPG, FLC, BHY, XDU, ?

TZQ

Explanation:

JPG, FLC, BHY, XDU, ?

The logic followed here is :

J → (-4) → F → (-4) → B → (-4) → X → (-4) → T

P → (-4) → L → (-4) → H → (-4) → D → (-4) → Z 

G → (-4) → C → (-4) → Y → (-4) → U → (-4) → Q

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