Select the option that is related to the third letter-cluster in the same way as the second letter-cluster is related to the first letter-cluster.
NEPHEW : QFOXFI : : PRIMER : ?

Let's examine the shift pattern by splitting the 6-letter word into two halves: NEP and HEW.
Reverse the first half: PEN

P + 1 = Q

E + 1 = F

N + 1 = O

This gives QFO.

Reverse the second half: WEH

W + 1 = X

E + 1 = F

H + 1 = I

This gives XFI.

Combining both halves gives QFOXFI. The logic is: Reverse each half of the 6-letter word and add +1 to every letter.

Let's apply this exact logic to PRIMER:

Split into two halves: PRI and MER.

Reverse the first half: IRP

I + 1 = J

R + 1 = S

P + 1 = Q

First half code = JSQ

Reverse the second half: REM

R + 1 = S

E + 1 = F

M + 1 = N

Second half code = SFN

Combining both parts gives JSQSFN.