The correct answer is: "a cultural mediator".
Sacagawea was an indegenous woman from the Shoshone indians who participated in the expedition leaded by Lewis and Clark, as a guide. She arrived in the expedition with her husband, Toussaint Charbonneau, who was a French explorer.
The expedition aimed to explore the Western regions of North America, beginning near St. Louis and ended up reaching the current state of Oregon. It took place between 1804 and 1806.
She was crucial in her contributions as guide, indicating how to safely arrive to the Pacific Ocean, but also because she established cultural contacts with the different groups of native people that they encountered in their way.