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.

KTM : PGN :: ABC : ?

ZYX

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

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

KTM : PGN :: ABC : ?

The  logic followed here is :

K → (OPPOSITE) → P

T → (OPPOSITE) → G

M → (OPPOSITE) → N

SIMILARLY

A → (OPPOSITE) → Z

B  → (OPPOSITE) → Y

C  → (OPPOSITE) → X