I don't know who De Vaca is but by context clues I would infer that he realized that Native Americans where not the savages they where thought to be.
The answer would be the Celsius scale
A divided opposition contributes to an increase of violence because it divides the people, government, etc. It leads to an increase of tension between different groups which in result, leads to an increase of violence.
Answer:
an individual personal sense of having a particular gender
