Select the term that will come next in the following series.

ELFA, GLHA, ILJA, _____, MLNA

KLLA

Explanation:

ELFA, GLHA, ILJA, _____, MLNA

The logic followed here is :

E → (+2) → G → (+2) → I → (+2) → K → (+2) → M 

L → (0) → L → (0) → L → (0) → L → (0) → L

F → (+2) → H → (+2) → J → (+2) → L → (+2) → N

A → (0) → A → (0) → A → (0) → A → (0) → A 

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