The correct answer is option C, that is, anthropology.
The study of humans and human behavior and societies in the present and the past is known as anthropology. The cultural and social anthropology study the values and norms of the societies. The linguistic anthropology studies that how the language influences social life. The physical or biological anthropology studies the biological development of humans.
Thus, anthropology studies about human nature and activities, therefore, an anthropologist can help in changing the behavior of poachers, as they illegally kill animals for their precious parts.
