What kept many indigenous people in Brazil’s interior isolated from the modern world?

Question

a)visitors being attacked with primitive weapons
b)the difficulty of traveling in the rain forest
c)the lack of roads and navigable rivers
d)tropical diseases that made most visitors sick

Answer 1

There are two of those answers that have to do with indigenous people's geographic isolation. Please read your text to decide which one answers this particular question.

Answer 2

What is the answer

Answer 3

Read your text and find out!

Answer 4

jerk