Answer:
Interactions between humans and the environment
Explanation:
This is one of the main themes that the historian will be studying. The study of history can be divided in a few major historical themes. This is because many historical events follow similar patterns or deal with similar problems. In this case, if the historian studies the effects of industrial air pollution on sugarcane farms, he is studying the interactions between humans and the environment. This is a theme that can be traced back to the development of agriculture.
