Given the task definition and input, reply with output. 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: a number increased by 40 % gives 700 . the number is 
Options: a ) 250 , b ) 500 , c ) 450 , d ) 500 , e ) 520

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
b