Which is true of primary sources but not secondary sources? (world history)

ANSWER:

A historical document which is used by historians as evidence is true about primary source.

EXPLANATION:

Primary sources are known to be the actual historical event which was originated or made during any of the historical events which were researched, told or recorded by any other person who has witnessed the situation in the following era. Secondary sources are the method to analyze any of the historical event from a certain objective point of view. Secondary sources are basically the ways in which comparison and study is done with primary source.

Andrei karlov was the russian ambassador