Explanation:

Alright, let’s dig into the pattern:

- Let's look at the first letters: F, I, L, ?, R

F to I (+3), I to L (+3), so the missing letter is L + 3 = O.

- Now, the middle letters: U, X, A, ?, G

U to X (+3), X to A (+3 if cycling after Z; X->Y->Z->A), so each is +3. A + 3 = D.

- Last letters: V, W, X, ?, Z

V to W (+1), W to X (+1), so X + 1 = Y, Y + 1 = Z. The missing one should be Y.

So the fourth cluster is ODY.

Now-let’s check the options:

- Option 1: PCY — the first letter should be O, not P.

- Option 2: PCX — first letter’s wrong, and third letter’s wrong.

- Option 3: ODY — That’s exactly what we found!

- Option 4: OCW — again, wrong letters.

Hope that clears things up! It’s satisfying when the pattern just locks into place.