Which is the best example of a primary source document useful in the study of history?
a) a documentary with expert analysis of the event in question.
b) a peer-reviewed article written about the event by a respected historian.
c) a professiorial analysis of key battlefield strategies of the event.
d) a journal excerpt from a person involved in the event in question.

The fourth alternative is correct (D).

History is usually narrated in a secondary way, through specialized observers of a particular context - historians.

However, although with less incidence, there are stories that are narrated by primary sources. The fact that it is a primary source means that the information comes from someone who has experienced that historical moment, that is, it is an in loco narration. In a way, it is a privileged view that is usually valued by historians.

An example of this may be a diary of someone who is involved in a war.

#1 im pretty sure its a.

either b) they were often feared and despised by other native cultures. or

c) their obsession allowed them to coexist with many other native cultures because of their peaceful nature.