In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: a man is 24 years older than his son . in six years , his age will be twice the age of his son . the present age of the son is 
Options: a ) 14 years , b ) 28 years , c ) 20 years , d ) 22 years , e ) none
Example Output: e

Example Input: Problem: the manager at a health foods store mixes a unique superfruit juice cocktail that costs $ 1399.45 per litre to make . the cocktail includes mixed fruit juice and a ç ai berry juice , which cost $ 262.85 per litre and $ 3104.35 per litre , respectively . the manager has already opened 33 litres of the mixed fruit juice . how many litres of the a ç ai berry juice does he need to add ? 
Options: a ) 17 litres , b ) 22 litres , c ) 11 litres , d ) 07 litres , e ) 38 litres
Example Output: b

Example Input: Problem: 23 × 19 × ? ÷ 19 ÷ 17 = 115 
Options: a ) 65 , b ) 75 , c ) 85 , d ) 95 , e ) 45
Example Output:
c