Answer:
They went on the Oregon Trail.
The answer would be the letter B
The American Revolutionary War, the Declaration of Independence, and the birth of the two-party system — this is a pivotal period in American history.
The answer is B.
The Great Migration was the movement of six million African Americans from the Southern U.S. to the North. As you probably know, back in the 1900's, segregation of African Americans was on the rise. At the time, the North was not involved in this segregation, so African Americans migrated to the Northern states to escape discrimination.
I think its a) one event happened only as a result of the other