The correct answer is C) A historian creates a graph of the economic strength of various empires throughout history.
The historian that has organized her study of the past based on the category "theme" is "A historian creates a graph of the economic strength of various empires throughout history."
To do this the historian has to prepare correct and deep research using proper and valid primary and secondary resources in order to develop her essay and support her arguments. She needs to include valid data and support it with facts, testimonies, statistics, audios, and videos to present indisputable evidence.