Historian interviews two people who fought during a certain battle during the Gulf War. One person says U.S. forces fired first; the other person says Iraqi forces fired first. To try to learn what really happened, the historian should:
A: believe the person who appears to be more trustworthy
B: believe the person who fought on the winning side
C: interview U.S and Iraqi citizens who learned about the battle in school
D: interview more soldiers who fought during the battle and compare their answers