What Is the Major Difference Between Ethnography and Other Kinds

What is the major difference between ethnography and other kinds of systematic observation used by social scientists? In ethnography

A) scientists interact with the people they are observing.
B) the people who are observed are paid for their part in the research study.
C) scientists randomly assign people to conditions.
D) scientists observe anything that seems surprising or interesting.
E) scientists record their own behaviours, as well as the behaviours of others.