D, because that one starts with "why" which automatically opens it up for an argument. While the others are just simply statements or just a basic question.
Answer:
The establishment of three U.S. army forts along the Bozeman trail through Lakota annexed Crow Indian treaty territory caused Red Cloud's war. The Crows fought back against the Indian trespassers by helping the troops in the very same forts that Red Cloud wanted closed.
Explanation:
Answer: The last one
Explanation: People must constantly fight enemies.
