The correct answer is option b. "Native Americans learned new techniques of irrigation".
Explanation:
Westward expansion was a period where almost 7 million Americans migrated to the westward looking to prosper in a new land. This was a rough era for Native Americans since they were forced to leave their lands and live in reserves. Even though westward expansion brought technology to this area of the United States, natural resources were depleted and natives suffered from new diseases that Americans brought from other places. One effect that was not related to the westward expansion was Native Americans learning new techniques of irrigation, since the expansion did not involve giving technology to Native Americans
