The Great Atlantic Migration can be explained by a combination of the factors listed, but one of the most prominent theories involves economic push factors in Europe resulting from crop failures. These failures often led to poverty and hardship, prompting individuals and families to seek better opportunities in the U.S.
However, another critical aspect of the migration includes economic pull factors in Europe due to industrial growth, as industrialization created job opportunities that attracted migrants to the U.S.
In summary, while all the options listed have relevance to the migration phenomenon, economic push factors in Europe resulting from crop failures is likely the most fitting response for forming a theory specifically explaining the Great Atlantic Migration.