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: how many liters of water must be evaporated from 50 liters of a 2 - percent sugar solution to get a 10 - percent solution ? 
Options: a ) 25 , b ) 30 , c ) 35 , d ) 40 , e ) 45

Output: d


Input: Consider Input: Problem: 90 students represent x percent of the boys at jones elementary school . if the boys at jones elementary make up 50 % of the total school population of x students , what is x ? 
Options: a ) 134 , b ) 150 , c ) 225 , d ) 250 , e ) 500

Output: a


Input: Consider Input: Problem: the present population of a town is 2100 . population increase rate is 5 % p . a . find the population of town before 1 years ? 
Options: a ) 1500 , b ) 1600 , c ) 2000 , d ) 2100 , e ) 2500


Output: c