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'.

Input: Consider Input: Problem: robert ate 13 chocolates , nickel ate 4 chocolates . how many more chocolates did robert ate than nickel ? 
Options: a ) a ) 4 , b ) b ) 7 , c ) c ) 9 , d ) d ) 5 , e ) e ) 2

Output: c


Input: Consider Input: Problem: solution x is 10 percent alcohol by volume , and solution y is 30 percent alcohol by volume . how many milliliters of solution y must be added to 150 milliliters of solution x to create a solution that is 25 percent alcohol by volume ? 
Options: a ) 250 / 3 , b ) 500 / 3 , c ) 400 , d ) 450 , e ) 600

Output: d


Input: Consider Input: Problem: dan ' s age after 16 years will be 6 times his age 4 years ago . what is the present age of dan ? 
Options: a ) 8 , b ) 10 , c ) 12 , d ) 14 , e ) 16


Output: a