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'.

Input: Consider Input: Problem: find the c . i . on a sum of rs . 10000 for 6 months at 20 % per annum , interest being compounded halfyearly ? 
Options: a ) 3010 , b ) 2010 , c ) 1000 , d ) 3100 , e ) 2100

Output: c


Input: Consider Input: Problem: an error 2 % in excess is made while measuring the side of a square . the percentage of error in the calculated area of the square is : 
Options: a ) 1.04 , b ) 2.04 , c ) 3.04 , d ) 4.04 , e ) none of these

Output: d


Input: Consider Input: Problem: peter invested a certain sum of money in a simple interest bond whose value grew to $ 100 at the end of 2 years and further to $ 200 at the end of another 4 years . what was the rate of interest in which he invested his sum ? 
Options: a ) 50 % , b ) 25 % , c ) 10 % , d ) 30 % , e ) 18 %


Output: a