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: if n is an integer , f ( n ) = f ( n - 1 ) - n and f ( 4 ) = 14 . what is the value of f ( 6 ) ? 
Options: a ) 3 , b ) 0 , c ) 1 , d ) 2 , e ) 4

Output: a


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: what is the sum of the local values of the digits 2 , 3 , 4 , 5 in the number 2345 ? 
Options: a ) 2345 , b ) 4500 , c ) 5000 , d ) 6000 , e ) 7000


Output: a