How Does the Modern World System Affect Ethnographers

How does the modern world system affect ethnographers?

A) There are almost no truly isolated cultures left, making it difficult to do real ethnographic research.
B) They need to be aware of the fact that any culture they study is influenced by and has influence on other cultures.
C) They must be careful when comparing their findings to those who did work in the first half of the 20^th century, when there were many isolated cultures.
D) There are no more indigenous peoples.
E) It has brought about a blending of the races, which makes it harder to identify specific cultures.