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 is two years older than b who is twice as old as c . if the total of the ages of a , b and c be 12 , the how old is b ? 
Options: a ) 10 years , b ) 4 years , c ) 6 years , d ) 15 years , e ) 16 years
Example Output: b

Example Input: Problem: the average weight of a , b , c is 45 kg . the avgwgt of a & b be 40 kg & that of b , c be 43 kg . find the wgt of b . 
Options: a ) 23 , b ) 43 , c ) 21 , d ) 31 , e ) 43
Example Output: d

Example Input: Problem: a man â € ™ s current age is ( 2 / 5 ) of the age of his father . after 10 years , he will be ( 1 / 2 ) of the age of his father . what is the age of father at now ? 
Options: a ) 40 , b ) 45 , c ) 38 , d ) 50 , e ) 39
Example Output:
d