Select the set in which the numbers are related in the same way as are the numbers of the given sets.

(NOTE : Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 - Operations on 13 such as adding /subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)

(7, 12, 25)

(6, 9, 21)

(5, 8, 19)

(7, 12, 25)

(6, 9, 21).

The logic followed here is :

(Ist number + second number) + 6  = Third number 

As

(7 +12) + 6 = 25

(6 + 9) + 6 = 21

Same as in option 2  (5, 8, 19)

(5 + 8) + 6  = 19