The theory explaining the Great Atlantic Migration can be formed by considering multiple factors, but one of the most significant components is the combination of economic push factors in Europe resulting from crop failures and political push factors in Europe due to governmental instability. These factors often compelled people to leave their countries in search of better opportunities in the U.S., where there were substantial economic pull factors, such as jobs and land availability.
Among the options you've provided, the most fitting responses would be:
- economic push factors in Europe resulting from crop failures
- political push factors in Europe due to governmental instability
Both of these options highlight the reasons that drove migrants from Europe to the United States during this period. Economic pull factors in the U.S. could also be considered a part of the overall theory, but they are not stated explicitly in this list.