Three of the following four letter-clusters are alike in a certain way and one is different.
Pick the odd one out.

Write each letter’s position in the English alphabet:
$$A=1, \, B=2, \ldots ,\, Z=26$$

Convert every letter-cluster into numbers:

Option A : $$X\,L\,Q \;\to\; 24,\,12,\,17$$
Option B : $$Z\,N\,S \;\to\; 26,\,14,\,19$$
Option C : $$Q\,E\,J \;\to\; 17,\,5,\,10$$
Option D : $$W\,K\,O \;\to\; 23,\,11,\,15$$

Now examine the jumps from the 1st letter to the 2nd and from the 2nd to the 3rd.

Case 1: Option A (24,12,17)
  • First jump: $$24-12 = 12\;(\text{down by }12)$$
  • Second jump: $$17-12 = 5\;(\text{up by }5)$$ Case 2: Option B (26,14,19)
  • First jump: $$26-14 = 12\;(\text{down by }12)$$
  • Second jump: $$19-14 = 5\;(\text{up by }5)$$ Case 3: Option C (17,5,10)
  • First jump: $$17-5 = 12\;(\text{down by }12)$$
  • Second jump: $$10-5 = 5\;(\text{up by }5)$$ Case 4: Option D (23,11,15)
  • First jump: $$23-11 = 12\;(\text{down by }12)$$
  • Second jump: $$15-11 = 4\;(\text{up by }4)$$

Observation: In Options A, B and C the rule “down by 12, then up by 5” holds exactly. Option D breaks the rule because the second jump is only $$4$$, not $$5$$.

Hence the odd one out is
Option D which is: WKO