What was the main reason the United States got involved in the Korean and Vietnam wars

The main reason for both the wars is that the United States did not want Communism to spread in Southeast Asia (also the world). The Domino Theory states that if one country were to become communist, then other countries would follow until there were communist countries everywhere. The US was simply trying to protect their own interests.

Explanation:

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: