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

PLAN : QOMKBZOM :: SINK : TRJHOMLJ :: RUDE: ?

SQVTECFD

1   2    3    4   5    6   7     8    9  10  11  12  13

 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

PLAN : QOMKBZOM :: SINK : TRJHOMLJ :: RUDE: ?

The logic;

(each letter is increased and decreased by 1 positional value)

Thus, SQVTECFD is correct.