Select the option that is related to the third letter-pair in the same way as the second letter pair is related to the first letter-pair. RG : QE :: LB : ?

KY KZ JZ JY

KZ

Pattern followed is :  RG: QE  R(18) -1 = (17)Q , G(7) - 2  = (5)E  Similarly ,  LB : ?  L(12) -1 = (11)K , B(2) -  2 = Z  KZ , is correct answer .