Select the option that is related to the fifth letter-cluster in the same way as the second letter-cluster is related to the first letter-cluster and the fourth letter-cluster is related to the third letter-cluster.
CARS : HFWX :: BOAT : GTFY :: FUSE : ?

Let's check the relation between the corresponding letters of the clusters by their positional values:
1. **CARS $\to$ HFWX**:
* C (3) $\stackrel{+5}{\to }$ H (8)
* A (1) $\stackrel{+5}{\to }$ F (6)
* R (18) $\stackrel{+5}{\to }$ W (23)
* S (19) $\stackrel{+5}{\to }$ X (24)
The pattern is adding $+5$ to each letter.

2. **BOAT $\to$ GTFY**:
* B (2) $\stackrel{+5}{\to }$ G (7)
* O (15) $\stackrel{+5}{\to }$ T (20)
* A (1) $\stackrel{+5}{\to }$ F (6)
* T (20) $\stackrel{+5}{\to }$ Y (25)
The pattern $+5$ is verified.

Applying the same logic to FUSE:

* F (6) $\stackrel{+5}{\to }$ K (11)
* U (21) $\stackrel{+5}{\to }$ Z (26)
* S (19) $\stackrel{+5}{\to }$ X (24)
* E (5) $\stackrel{+5}{\to }$ J (10)

The resulting letter-cluster is KZXJ.