It is implied in the last paragraph that the method used by earlier ethnographers was ______.

A．developed ethnography into anthropology
B．used tape recorders to record the desired information
C．studied such units as urban ghettos
D．is considered father of ethnography

A．current conditions that exist with a culture
B．individual behavior as shaped by a custom
C．behavior patterns common among members of a culture
D．differences existing within a culture