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 rainstorm increased the amount of water stored in state j reservoirs from 124 billion gallons to 140 billion gallons . if the storm increased the amount of water in the reservoirs to 80 percent of total capacity , approximately how many billion gallons of water were the reservoirs short of total capacity prior to the storm ? 
Options: a ) 51 , b ) 48 , c ) 55 , d ) 63 , e ) 65
Example Output: a

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 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
Example Output: d

Example Input: Problem: 248 : 3 : : 328 : ? 
Options: a ) 7 , b ) 5 , c ) 4 , d ) 6 , e ) none of the above
Example Output:
c