Final answer:
Anthropology is a unified field in the United States due to its holistic approach, shared research methods, and ethical guidelines which make it capable of providing a broad, interconnected understanding of human experience.
Step-by-step explanation:
In the context of United States, anthropology is commonly considered a unified field due to several reasons. The correct option is b) Holistic approach, shared research methods, ethical guidelines. Several things unify the field, but paramount among them are the following: