Final answer:
Sacagawea was the Indian woman who helped Lewis and Clark on their exploration. She served as an interpreter and diplomat, along with her husband Toussaint Charbonneau, who was hired as a guide. Her presence with an infant helped dispel fears that the expedition was hostile.
Step-by-step explanation:
The Indian woman who helped Lewis and Clark on their exploration of the Louisiana Territory was Sacagawea. She played a vital role in the expedition as an interpreter and diplomat to the Shoshone people. Sacagawea was brought along by French fur trader Toussaint Charbonneau, who was hired as a guide and interpreter by the expedition. Her presence as a young woman with an infant helped convince many Native American groups that the expedition was not a war party.