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: 123 : 36 : : 221 : ? 
Options: a ) 52 , b ) 69 , c ) 72 , d ) 25 , e ) 32
Example Output: d

Example Input: Problem: if one root of the equation 2 x ^ 2 + 3 x – k = 0 is 5 , what is the value of k ? 
Options: a ) 65 , b ) 79 , c ) 68 , d ) 87 , e ) 90
Example Output: a

Example Input: Problem: the average weight of 9 person ' s increases by 2.5 kg when a new person comes in place of one of them weighing 65 kg . what is the weight of the new person ? 
Options: a ) 85.5 , b ) 86.5 , c ) 87.5 , d ) 88.5 , e ) 89.5
Example Output:
c