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 sale of sleeping bags , a retailer made a gross profit of 14 % of the wholesale cost . if each sleeping bag was sold for $ 28 , what was the wholesale cost per bag ? 
Options: a ) 3.0 , b ) 3.36 , c ) 24.56 , d ) 25.0 , e ) 31.36
Example Output: c

Example Input: Problem: i sold a book at a profit of 10 % . had i sold it for $ 150 more , 15 % would have been gained . find the cost price ? 
Options: a ) $ 2000 , b ) $ 2500 , c ) $ 3000 , d ) $ 3120 , e ) $ 1540
Example Output: c

Example Input: Problem: a man can row 24 kmph in still water . it takes him thrice as long to row up as to row down the river . find the rate of the stream ? 
Options: a ) 6 , b ) 12 , c ) 18 , d ) 15 , e ) 20
Example Output:
b