Select the option that is related to the third letter-cluster in the same way as the second letter-cluster is related to the first letter-cluster.

LON : RRN :: MAD : ?

HDO

A   B   C    D   E    F   G    H    I    J    K    L   M

 ↓    ↓    ↓    ↓    ↓     ↓   ↓    ↓     ↓   ↓    ↓    ↓    ↓

 Z   Y    X   W   V    U   T    S    R   Q   P    O   N

26  25  24  23  22  21  20  19  18  17  16  15  14

******************************************

LON : RRN :: MAD : ?

The  logic followed here is :

REVERSE THE ALPHABET PATTEN

LON = NOL

N → (+2) → R

O→ (+3) → R

L → (+4) → N

SIMILARLY

MAD = DAM

D → (+2) → H

A → (+3) → D

M → (+4) → O