Anthropologists, When Studying Culture, Try to Distinguish Actual Behavior from Ideas

Anthropologists, when studying culture, try to distinguish actual behavior from ideas about how people ought to feel and behave. This is because

A) there is often a difference between ideal behavior and actual behavior.
B) the ideal is based on the way a society used to be.
C) ideal behavior may be what they would like to see as correct behavior.
D) all of the above.