Why is Napoleon Chagnon considered "America's most controversial anthropologist?"

A. He challenged romantic notions of man in a natural state of altruism and peace-loving, by describing the Yanomamö as a violent tribe in a "constant state of warfare," whose males"derive status and women from killing rivals."
B. Many of Chagnon's peers considered his conclusions on the intrinsic, biologically-based violence to be racist and simplistic with exaggerated claims of brutality.
C. Allegations of unethical fieldwork practices towards Chagnon surfaced in a book published by a journalist in 2000 (which later were found to mostly be false) that ignited a firestorm of controversy against Chagnon from his peers and organizations including the American Anthropological Association.
D. All the above