Select the option in which the two numbers are related in the same way as are the numbers in the given number-pair.
40 : 19 :: ?

40 ==> $$\frac{40}{2}-1$$ = 20-1 = 19

Option (a) 46 : 23

46 ==> $$\frac{46}{2}-1$$ = 23-1 = 22

The given logic is not applicable here. So this is not the correct answer.

Option (b) 34 : 17

34 ==> $$\frac{34}{2}-1$$ = 17-1 = 16

The given logic is not applicable here. So this is not the correct answer.

Option (c) 28 : 13

28 ==> $$\frac{28}{2}-1$$ = 14-1 = 13

The given logic is applicable here. So this is the correct answer.

Option (d) 20 : 11

20 ==> $$\frac{20}{2}-1$$ = 10-1 = 9

The given logic is not applicable here. So this is not the correct answer.

Hence option (c) is the correct answer.