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: what is the rate percent when the simple interest on rs . 4000 amount to rs . 320 in 2 years ? 
Options: a ) 4 % , b ) 4.1 % , c ) 4.2 % , d ) 4.3 % , e ) 4.5 %
Example Output: a

Example Input: Problem: a car dealership has 40 cars on the lot , 30 % of which are silver . if the dealership receives a new shipment of 80 cars , 40 % of which are not silver , what percentage of total number of cars are silver ? 
Options: a ) 35 % , b ) 37.5 % , c ) 45 % , d ) 47.5 % , e ) 50 %
Example Output: e

Example Input: Problem: a man is walking at the rate of 9 km / hr crosses a bridge in 15 minutes . the length of the bridge is 
Options: a ) 1000 meters , b ) 1050 meters , c ) 2200 meters , d ) 2250 meters , e ) none of these
Example Output:
d