You are writing an essay about the experiences of 19th century american frontiersmen. if you wished to show that these men had a tough and hearty spirit, which source would be best to cite? a) a book about the first settlements in the american west b) a clip from a video in which the terrain of the american west is analyzed c) a magazine describing the artillery used by 19th century american frontiersmen d) an excerpt from a personal diary in which a frontiersman describes a difficult trek through a snowstorm