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: in one hour , a boat goes 8 km along the stream and 2 km against the stream . the sped of the boat in still water ( in km / hr ) is : 
Options: a ) 3 , b ) 5 , c ) 8 , d ) 9 , e ) 10
Example Output: b

Example Input: Problem: ravi purchased a refrigerator and a mobile phone for rs . 15000 and rs . 8000 respectively . he sold the refrigerator at a loss of 5 percent and the mobile phone at a profit of 10 percent . overall he make a . 
Options: a ) 50 , b ) 288 , c ) 27 , d ) 200 , e ) 881
Example Output: a

Example Input: Problem: a man gains 30 % by selling an article for a certain price . if he sells it at double the price , the percentage of profit will be . 
Options: a ) 130 % , b ) 140 % , c ) 150 % , d ) 260 % , e ) 170 %
Example Output:
d