Select the option that is related to the fifth letter-cluster in the same way…

To solve the analogy CWE : ZFX :: PYT : MDI :: KIL : ?, we need to determine the rule governing the relationship between the letter-clusters in each pair.

Step-by-Step Analysis
Let's convert the letters to their numerical positions in the alphabet (A=1, B=2, ..., Z=26) to find the shifts.

Pair 1: CWE : ZFX

C (3) to Z (26): 3 - 3 = 0, which wraps around to 26 (-3)

W (23) to F (6): 23 + 9 = 32; 32 - 26 = 6 (+9)

E (5) to X (24): 5 - 7 = -2; 26 - 2 = 24 (-7)

Pattern: -3, +9, -7

Pair 2: PYT : MDI

P (16) to M (13): 16 - 3 = 13 (-3)

Y (25) to D (4): 25 + 5 = 30; 30 - 26 = 4 (+5) ... Wait, let's re-examine.

Alternative approach: Reversed alphabet or simple shifts
If we look at C to Z, W to F, E to X:

C + Z = 29

W + F = 29

E + X = 29

This reveals the pattern is that each letter is paired with one that sums to 29 (or simply a specific shift pattern).

Let's apply the Sum to 29 rule:

K + ? = 29 -> 11 + ? = 29 -> ? = 18 (R)

I + ? = 29 -> 9 + ? = 29 -> ? = 20 (T)

L + ? = 29 -> 12 + ? = 29 -> ? = 17 (Q)

Conclusion
The relationship in each pair is that the sum of the positions of corresponding letters is 29 (e.g., C(3) + Z(26) = 29). Applying this to KIL:

K(11) + R(18) = 29

I(9) + T(20) = 29

L(12) + Q(17) = 29

The correct cluster is RTQ.