Which of the following statements about slavery in the early 19th century is true? a.) The federal government abolished the international slave trade in 1808, but slavery proliferated nonetheless.

b.) Gradual emancipation was instituted in 1808 in the South to help its economy transition away from slavery.

c.) Slavery was illegal starting in 1808, but southern states nullified federal law.

d.) After 1808, slaves could no longer buy their freedom, and free southern blacks were forced into slavery.

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation:

answer: the unlawful use of violence and intimidation, especially against civilians, in the pursuit of political aims.

explanation:

if i am correct the answer is going to be a) the federal program of reconstruction ended.