The correct answer is the following.
Unfortunately, you did not attach the article. You forgot to include the article, the title of it, or the name of the author. Without that important information, it is very difficult to answer your question because we do not know the content of the article.
However, trying to help you with some information we can comment on the following general terms.
The Native Americans that helped Lewis And Clark in a significant way during their expedition of the recently acquired Louisiana territory were the Lemi Shoshone. These Indians were led by Chief Cameahwait. The Native Indians helped with translation to better communicate with the explorers.
That is how the members of the Lewis and Clark expedition could get the so much-needed supplies and food before winter and keep on with the exploration. So from your options, and without knowing the content of the article that you did not attach, it is probable that the section could have been "mixed relations with Native Americans."