Which accurately describes a chart developed 20 years after a historical event?Which accurately describes a letter written during the time a historical event occurred?

this is a very vague question

Explanation:

historians actually date events after about 50 years

answer:

the majority of cambodians living today were born after the khmer rouge was ousted in 1979 and some who survived can forget how bad it was. when khmer rouge forces seized phnom penh on april 17, 1975, the couple was living with eight of their children in a rural town called kampong chhnang.

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: