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: at what rate percent per annum will the simple interest on a sum of money be 4 / 5 of the amount in 10 years ?
Options: a ) 4 % , b ) 7 % , c ) 8 % , d ) 3 % , e ) 1 %
Example Output: c

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: 20 is subtracted from 60 % of a number , the result is 88 . find the number ?
Options: a ) 120 , b ) 300 , c ) 180 , d ) 170 , e ) 148
Example Output:
c