The trail lines on the map above represent the trails taken by pioneers migrating to the west. what was the likely effect of these trails on the western regions? a) over time, development occurred all along the trails not just at the end. b) the trails had little impact on the regions and quickly disappeared after the rush. c) along the way, settlers destroyed the land and polluted all the natural resources. d) once they reached the end, settlers returned to various points along the trail they liked better.