Explanation:

Let's break down the pattern in the series:

- RIN

- TFR

- VCV

- ?

- ZWD

Let's look at the positions of each letter in the alphabet:

1st Position: R (18), T (20), V (22), ?, Z (26)

2nd Position: I (9), F (6), C (3), ?, W (23)

3rd Position: N (14), R (18), V (22), ?, D (4)

Pattern in each position:

- First letter: +2 each time (R, T, V, X, Z)

- Second letter: -3 each time (I, F, C, Z, W)

- I (9) to F (6): -3

- F (6) to C (3): -3

- C (3) to Z (26): (Wrap around alphabet, 3-3 = 0, which is Z as 26)

- Z (26) to W (23): -3

- Third letter: +4 each time, wrap after "Z"

- N (14), R (18), V (22), Z (26), D (4)

Now, insert missing values:

- 1st: V+2 = X

- 2nd: C-3 = Z

- 3rd: V+4 = Z (V=22+4=26=>Z)

So the missing cluster is XZZ.

Options:

- ZZZ

- YZA

- YZZ

- XZZ

Correct answer is XZZ.