Crossing the great plains, hope this helps! :)
Answer:
Option D is correct.
Explanation:
There were pull and push factor which led to the westward migration in the USA. They migrated in large numbers from the stats of Ohio, Indian, Illinois, and New York. Trouble in getting farmland was one reason, while lucrative offers by the government to occupy, till and buy the lands in the west attracted people who required the land. The opportunity to mine precious metals was also an equally important reason. Overcrowding of towns in the East and Low wages were the push factors.
I think the answer might be the second one but t let me know if I am wrong