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: if an article is sold at 18 % profit instead of 9 % profit , then the profit would be $ 54 more . what is the cost price ? 
Options: a ) $ 500 , b ) $ 600 , c ) $ 700 , d ) $ 800 , e ) $ 900
Example Output: b

Example Input: Problem: two boys starts from the same place walking at the rate of 5.5 kmph and 7.5 kmph respectively in the same direction . what time will they take to be 32 km apart ? 
Options: a ) 18 , b ) 16 , c ) 19 , d ) 15 , e ) 34
Example Output: b

Example Input: Problem: find the compound interest on $ 1200 for 2 years at 20 % p . a . if ci is component yearly ? 
Options: a ) $ 120 , b ) $ 150 , c ) $ 548 , d ) $ 250 , e ) $ 300
Example Output:
c