How many documents made up the treaty for the purchase for the louisiana territory

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:

"germany's geographic location was an advantage when it was on the offensive in the war because it was situated next to an extremely wide river, the rhine, which was difficult for the allies to cross."