Explanation:

- Let's look at the patterns in the letter series: WUE, XXG, YAI, ?

- The first letter pattern goes from W to X to Y, so the next should be Z.

- The second letter pattern is U to X to A, which is a reverse alphabet sequence. A is the first letter, so it wraps back. After A (with reverse counting), it would be D.

- The third letter pattern is E to G to I, which increases by two letters each time. So, after I, it should be K.

- So, the sequence should be ZDK.

- Option 1: ZDK - Correct Answer

- Option 2: ZOK

- Option 3: ZBH

- Option 4: ZAJ

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