1 is related to 24 following a certain logic. Following the same logic, 16 is related to 84. To which of the following is 21 related, following the same logic?
(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.)

1 is related to 24 following a certain logic. Following the same logic, 16 is related to 84.

Logic: sum of both numbers becomes perfectly divisible by 5.

1+24 = 25 (perfectly divisible by 5)

and

16+84=100(perfectly divisible by 5)

Similarly,

21+108=129(not perfectly divisible by 5)

21+98=119(not perfectly divisible by 5)

21+104=125 (Perfectly divisible by 5)

21+112=133(not perfectly divisible by 5)