Which of the following is necessary to validate a claim about an event in history

documents proving it happened

Corroborated sources of historical evidence are the most necessary factor to validate situation or an event in history.

Explanation:

Historians are humans too, and they tend to use written sources as references, we all know written sources are not 100% true, audio visual materials and artifacts are very important objects that help to provide information to present historians.

Historical sources are usually classified into two subdivisions: primary and secondary sources. Depending on the historian's use or purpose, some sources move their choice. Figuring out what type of clues to implement, and the level of truth and reliability of these sources, is an important t step in thinking for the historians which makes them quite un reliable, which also makes corroborated sources more reliable  

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