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

Information Given:
Series: PDH, RFJ, THL, VJN, ?

Logic: Each letter increases by +2 positions in the alphabet.

Step-by-step:
First letters: P → R → T → V → X (+2)
Second letters: D → F → H → J → L (+2)
Third letters: H → J → L → N → P (+2)

Next term = X L P

Final Answer:
XLP

Final Correct Option:
(A)