According to the positional values of the alphabets, 1) XKE9 → X – K – E = 24 – 11 – 5 = 8 and not 9. This is odd. 2) ULD5 → U – L – D = 21 – 12 – 4 = 5 3) ZAT5 → Z – A – T = 26 – 1 – 20 = 5 4) YGA17 → Y – G – A = 25 – 7 – 1 = 17 Hence, the odd one among the given options is XKE9.