Select the option that is related to the third term in the same way as the second term is related to the first term and the sixth term is related to the fifth term.

8 : 2 :: 12 : ? :: 24 : 10

In the following number-pairs, the second number is obtained by applying certain
mathematical operations to the first number. Select the pair in which the numbers are
related in the same way as are the numbers of the following pairs.
(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.)
108, 54
78, 39

10 is related to 2 following a certain logic. Following the same logic, 45 is related to 9. To which of the following is 50 related, following the same logic?
(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into their constituent digits. E.g. 13 – Operations on 13 such as adding/subtracting/multiplying to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)​