The correct answer is A. Interview more soldiers who fought during the battle and compare their answers
Step-by-step explanation:
In general terms, historical events can be better understood by using firs-hand accounts or primary sources. This means to know what happened at an event the best is to look for documents or sources made by those who directly experienced the events, which includes testimonies. In this context, the best for this historian is to interview soldiers who participated in the battle and use this information to better understand the story, including which side fired first (Option A.)