Which of the following do anthropologists believe to be true? a. Few, if any, isolated groups have existed in human history. b. Undiscovered human groups likely remain in the Amazon rainforest. c. Most human groups are influenced by only one or two other cultures. d. Humans tend to be divided into two groups: tribal or modern.

Letter A is the correct answer.

Anthropologist believe that few, if any, isolated groups have existed in human history. Recently, in Brazil, an isolated indigenous tribe has emerged from the Amazon forest and made peaceful contact with villagers from the border of Peru. This indigenous tribe has got its own way of communicating and can act in a very strange way but is very much aware of the presence of outsiders.