Find the odd one out?

The correct option is JLN.

To find the odd one out, let's analyze the positions of the letters in the English alphabet for each option:

1. RUW:
R = 18
U = 21 (18 + 3)
W = 23 (21 + 2)
Pattern: +3, +2

2. PSU:
P = 16
S = 19 (16 + 3)
U = 21 (19 + 2)
Pattern: +3, +2

3. MPR:
M = 13
P = 16 (13 + 3)
R = 18 (16 + 2)
Pattern: +3, +2

4. FIK:
F = 6
I = 9 (6 + 3)
K = 11 (9 + 2)
Pattern: +3, +2

5. JLN:
J = 10
L = 12 (10 + 2)
N = 14 (12 + 2)
Pattern: +2, +2

All groups except JLN follow the pattern of increasing the alphabetical position by +3 and then by +2. Therefore, JLN is the odd one out.