The most relevant option among the given choices for understanding why two groups of people are in conflict would be B) Explain the groups were once in war.
Historians can provide insights into the historical context of conflicts between two groups by examining past wars, disputes, and tensions.
Understanding the historical events and circumstances that led to conflicts can shed light on the roots of animosity, grievances, or territorial disputes between the groups.
This option directly addresses the historical aspect of the conflict, making it a more comprehensive and insightful choice.
The most relevant option among the given choices for understanding why two groups of people are in conflict would be B) Explain the groups were once in war.