Which example best illustrates a primary research source?
a.
a documentary about the effects of the westward movement and homesteading on the prairie during the 1800s
b.
a novel that tells the story of one pioneer family's struggles crossing the prairie during the 1800s
c.
a historical analysis of life on the prairie during the 1800s
d.
the diary of a woman crossing the prairie in a covered wagon during the 1800s