Explanation:

- The relationship between the first two letter-clusters (PRO : NOL) involves moving each letter of "PRO" backward by two positions in the English alphabet to form "NOL":

- P to N (P is the 16th letter, N is the 14th, moving 2 steps back)

- R to O (R is the 18th letter, O is the 15th)

- O to L (O is the 15th letter, L is the 12th)

- For the letter-cluster HEL:

- H moves back two positions to become F

- E moves back two positions to become C

- L moves back two positions to become J

- Let's examine the options:

1. FIB

2. FCJ

3. FJC

4. FBI

The correct transformation of HEL is FCJ.

FCJ is the correct answer.