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.

TRO : QMN :: BLA : ?

YGZ

Pattern followed is :

TRO : QMN

T(20) - 3 = (17)Q , R(18) - 5 = (13)M , O(15) - 1 = (14)N

Similarly ,

BLA : ?

B(2) - 3 = (25)Y , L(12) - 5 = (7)G , A(1) - 1 = (26)Z

YGZ , is correct answer .