Because it is getting late
Answer: an encyclopedia article about the Civil War
Explanation:
An encyclopedia article is always the best source when trying to achieve a credible and accurate account of a historical event.
Letters from soldiers fighting in the Civil War might provide great insight, but their records will be quite subjective. The same happens with a user-uploaded video reenactment. A wiki user-generated content is not trustworthy enough. And the map might be useful but require further investigation to be used in the report.
If a statement is a simple sentence that describes something and doesn't lie, then some examples would be "A folktale is a legend." or "A folktale is a story that people tell." et cetera.
Answer:
I won't write you whole assignment for you. Ask a question about it.