Which letter cluster will replace the question mark (?) to complete the given series?
LAFI, MCGL, ?, OGIR, PIJU
Answer & explanation
Correct answer: option 3

Explanation:
LAFI, MCGL, ?, OGIR, PIJU
The logic followed here is :
L → (+1) → M → (+1) → N → (+1) → O → (+1) → P
A → (+2) → C → (+2) → E → (+2) → G → (+2) → I
F → (+1) → G → (+1) → H → (+1) → I → (+1) → J
I → (+3) → L → (+3) → O → (+3) → R → (+3) → U
So, the letter-cluster that replaces the (?) to complete the series is "NEHO"