Detailed Instructions: 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'.
Problem:Problem: at what rate percent per annum will a sum of money double in 10 years ? 
Options: a ) 10 % , b ) 15 % , c ) 18 % , d ) 20 % , e ) 25 %
Solution:
a