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: reena took a loan of $ . 1200 with simple interest for as many years as the rate of interest . if she paid $ 588 as interest at the end of the loan period , what was the rate of interest ? 
Options: a ) 3.6 , b ) 7 , c ) 18 , d ) can not be determined , e ) none of these
Example Output: b

Example Input: Problem: to produce an annual income of rs . 800 from a 8 % stock at 90 , what is the amount of stock needed ? 
Options: a ) 10000 , b ) 11000 , c ) 12000 , d ) 13000 , e ) 14000
Example Output: a

Example Input: Problem: how is 4 % expressed as a decimal fraction ? 
Options: a ) 0.4 , b ) 0.04 , c ) 0.004 , d ) 0.0004 , e ) 4
Example Output:
b