In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: from the beginning to the end of 2007 , the price of a stock rose 20 percent . in 2008 , it dropped 25 percent . in 2009 , it rose 25 percent . what percent of the stock â € ™ s 2007 starting price was the price of the stock at the end of 2009 ? 
Options: a ) 80 , b ) 90 , c ) 95 , d ) 100 , e ) 112.5
Example Output: e

Example Input: Problem: a tank contains 7,500 gallons of a solution that is 6 percent sodium chloride by volume . if 2,000 gallons of water evaporate from the tank , the remaining solution will be approximately what percent sodium chloride ? 
Options: a ) 5.18 % , b ) 6.18 % , c ) 7.18 % , d ) 8.18 % , e ) . 7 %
Example Output: d

Example Input: Problem: 80 % of a number is added to 120 , the result is the same number . find the number ? 
Options: a ) 600 , b ) 288 , c ) 1687 , d ) 997 , e ) 121
Example Output:
a