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: a man invests rs . 3,000 at the rate of 5 % per annum . how much more should he invest at the rate of 8 % , so that he can earn a total of 6 % per annum ? 
Options: a ) rs . 1200 , b ) rs . 1300 , c ) rs . 1500 , d ) rs . 2000 , e ) none of these
Example Output: c

Example Input: Problem: the simple interest on rs . 20 for 6 months at the rate of 5 paise per rupeeper month is 
Options: a ) 1.2 , b ) 1.4 , c ) 6 , d ) 7 , e ) none
Example Output: c

Example Input: Problem: running at the same constant rate , 6 identical machines can produce a total of 270 bottles per minute . at this rate , how many bottles could 20 such machines produce in 4 minutes ? 
Options: a ) 648 , b ) 1800 , c ) 2700 , d ) 10800 , e ) 3600
Example Output:
e