What system developed in medieval Europe in which knights or vassals served and protected kings or nobles in exchange for land

Which of the following statements best describes the terms of the treaty of guadalupe-hidalgo? a the treaty ended the mexican-american war, resulting in the u.s. finally being able to finish building railroads in texas. b the treaty ended the mexican-american war, resulting in mexico and the u.s. going back to their pre-war conditions. c the treaty ended the mexican-american war, resulting in the u.s. facing a lot of international backlash for the war. d this treaty ended the mexican-american war, resulting in mexico ceding a large amount of land to the united states.