Question

In 1976, a historian is writing about a book analyzing the causes of the american revolution, which was fought 200 years earlier. Which of the following sources would be a primary source he could consult?

Answer 1

A primary source is a source from the relevant time, done by someone who actually witnessed the event, not a source made later.

A primary source for a reasons of an event would be for example an opinion of a person from the time, so for example an opinion of a soldier of why they choose to participate in the war: best expressed in his own words, such as in a letter.