Answer:
The correct answer is D: interview civillians who are currently living in a warzone.
Step-by-step explanation:
A primary source is a firsthand source of information, created at the time of the study that took place. Therefore that a historian doing a study about war might interview civilians currently living in a warzone, because they will have regular experiences about the main topic of the study. In addition, the historian would have a variety of diverse views about the subject asked so that would increase the effectiveness of the study.