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: how many liters of water must be evaporated from 50 liters of a 1 - percent sugar solution to get a 10 - percent solution ? 
Options: a ) 35 , b ) 40 , c ) 42 , d ) 45 , e ) 48
d