The correct answer is D. The emancipation proclamation freed slaves only in states that had seceded from the union, is an example of a statement of evidence that can be used to support a claim about the civil war.
Historians use primary and secondary sources as evidence for their research. Primary sources are sources of information that were created at the time under the study, documents, manuscripts, diaries, are examples of these sources. In this case, the correct answer is a statement about a document that was created during that historical event, therefore it can be used as evidence. The rest of the answers are based on opinions or assumptions and cannot be used as evidence.
