<em>C. They believed if the Americans won they would continue to expand into Native American lands.</em>
Explanation:
The Native Americans favored the British during the Revolutionary War because they believed that if the Americans won the war they would continue to expand into Native American lands.
The main goal of the Native Americans was to protect their very important tribal lands. The Americans had started trying to take the lands, killing and sending off many Native Americans to do so. While the Native Americans also wanted to keep their tribal lands, they also wanted to open up trade with Great Britain and obtain new goods.
This can be seen as an example of "Manifest Destiny," where people believe that have a God-given destiny to expand, even if it is empowering over other people. While the term "Manifest Destiny" wasn't coined until westward expansion, the idea is prominent here as well.
Americans wanted to take the land they found that had belonged to the Native Americans, they did not care where that would stop, even if first confrontations were peaceful. They wanted to keep expanding no matter what.