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

24 : 171 :: ? :115 :: 4 : 31

16

Logic followed is:

(First number × 7) + 3 = Second number

24 : 171 

(24 × 7) + 3 = 168 + 3 = 171

4 : 31 

(4 × 7) + 3 = 28 + 3 = 31

? : 115

(x × 7) + 3 = 115

7x = 112

x = 16

16 , is correct answer .