Four letter-cluster have been given, out of which three are alike in some manner and one is different. Select the odd letter-cluster.

CEW, DFU, HJR, KMO

DFU

 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

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CEW =  C → (+2) → E → OPPOSITE +1 → W

DFU  = D → (+4) → F → OPPOSITE → F (THIS IS ODD)

HJR =   H → (+2) → J → OPPOSITE +1 → R

KMO =  K → (+2) →  M → OPPOSITE +1 → O