Which of the following letter-clusters will replace the question mark (?) in the given series?

ARC, EPF, JNI, PLL, ?

WJO

Explanation:

ARC, EPF, JNI, PLL, ?

The logic followed here is :

A → (+4) → E → (+5) → J → (+6) → P → (+7) → W

R → (-2) → P → (-2) → N → (-2) → L → (-2) → J

C → (+3) → F → (+3) → I→ (+3) → L → (+3) → O

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