Select the letter-cluster from among the given options that can replace the question mark (?) in the following series.
JFSX, KERY, ?, MCPA

Correct option is C

First letter in all terms follows logic (+1)
Second letter in all terms follows logic (- 1)
third letter in all terms follows logic (-1)
Fourth letter in all terms follows logic (+1)
K + 1 = L
E – 1 = D
R – 1 = Q
Y + 1 = Z
Option c is true.