a historian is awarded a grant to study the effects of industrial air pollution on sugarcane farms in brazil. his research will focus on which major historical theme?

His research will focus mainly in the reciprocal action between human and nature.

Explanation:

To really highlight the effects of pollution on sugar cane plantations, it's necessary to look for health related data to compare over the years.

Study the way food exposed to industrial air pollution affects people's daily lives; just as pesticides can cause various side effects such as cumulative poisoning, pollution from factories and cars can also contribute to similar ills.

A health analysis of people living in less polluted places compared to places with more pollution would be a good start for this research.