A. To support her argument that Native Americans were mistreated.
Explanation:
Answer B is incorrect because the passage does not give an interesting observation about what happens to other people, as she is the one being mistreated. Answer C is incorrect, because the wording in the passage states "Then I lost my spirit" and "I cried aloud, shaking my head all the while..." and "and heard them gnaw off one of my thick braids..." The wording in the passage shows how she is unhappy. D is wrong for essentially the same reason.
