1. What other countries besides the United States celebrate Black History Month?

Black History Month is an annual observance originating in the United States, where it is also known as African-American History Month. It has received official recognition from governments in the United States and Canada, and more recently has been observed in Ireland, the Netherlands, and the United Kingdom.

Explanation:

secretly cooperate with one another.

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: