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 sum of money lent out at s . i . amounts to a total of $ 480 after 2 years and to $ 680 after a further period of 5 years . what was the initial sum of money that was invested ? 
Options: a ) $ 360 , b ) $ 380 , c ) $ 400 , d ) $ 420 , e ) $ 440
Example Output: c

Example Input: Problem: what is the next number : 2 , 17 , 257 , __ 
Options: a ) 2977 , b ) 3837 , c ) 4097 , d ) 4847 , e ) 5387
Example Output: c

Example 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 300 milliliters of solution x to create a solution that is 15 percent alcohol by volume ? 
Options: a ) 50 , b ) 100 , c ) 150 , d ) 200 , e ) 250
Example Output:
b