It's one of the following:
1) Social Science
2) Sociology
3) Anthropology
I'm leaning towards social science, but there are far too many variables in what constitutes a probable, correct response to this particular question.
Answer: Hope it helps!
Explanation:
The one-drop rule is a social and legal principle of racial classification that was historically prominent in the United States in the 20th century. It asserted that any person with even one ancestor of sub-Saharan African ancestry ("one drop" of black blood) is considered black (Negro or colored in historical terms).