Are nobles higher in power or knights

Yes

Explanation:

Nobles were the upper ranks of society, usually having at least traces of royal blood. A noble who became a soldier would become a knight. They could even serve the same purpose, have the same equipment and even the same wealth but a knight would socially outrank a man at arms.

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: