What is this policy called when the first 150 years of its history the united states avoided becoming involved with other countries

Which of the following statements about the economic consequences of the civil war is not accurate. a. inflation caused prices to rise by 80% in the north. b. because southern farms cannot process enough food for everyone in the south the union navy allowed food shipments from britain. c. to pay for all of the food supplies and arrangements that were necessary for the union army congress instituted an income tax. d. business boomed in the north as factories and farms always had a market for their products.