Social anthropologists attempt to explain the social emergence, evolution and development of the human race. They also try to determine differences between human social organization and other primate beings. One of their attempts is note dissimilarity betyween various human societies. _____, all classifications of human socities and cultures may be arbitrary.
1. As a result
2. As usual
3. Moreover
4. However
(What is the most suitable expression in the blank in the passage?)