The highway system is a public enterprise. As the owner and operator, the various levels of Government have a responsibility for management that promotes the of the nation and serves the individual user.In the case of the Federal Government, expenditures on a highway program are a return to the highway user of the taxes which he pays in connection with his use of the highways. According to the passage,what is the source of the funds that the federal government uses for highway improvement? federal income taxes local property taxes taxes paid by highway users taxes paid by highway builders