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: the value of a machine depreciates at the rate of 10 % every year . it was purchased 3 years ago . if its present value is rs 8,748 , its purchase price was ? 
Options: a ) rs 16,000 , b ) rs 18,000 , c ) rs 12,000 , d ) rs 14,000 , e ) none of these
Example Output: c

Example Input: Problem: a sum of money at simple interest amounts to rs . 825 in 3 years and to rs . 846 in 4 years . the sum is ? 
Options: a ) s . 738 , b ) s . 638 , c ) s . 650 , d ) s . 762 , e ) s . 735
Example Output: d

Example Input: Problem: by selling a book for 260 , 20 % profit was earned . what is the cost price of the book ? 
Options: a ) a ) 215 , b ) b ) 216 , c ) c ) 230 , d ) d ) 235 , e ) e ) 240
Example Output:
b