The correct answer is the following: option D. The explosion of European immigration into the United States in the late 1800's can be best explained by the appearance of push factors in Europe and pull factors in America. From 1865 many Europeans began moving to the United States. This came as a consequence of poverty, social class restriction and political environment between other push factors. The United States was a good option for immigrants due to its pull factors, such as new job opportunities, the possibility of owing land and a more peaceful political environment, where everyone could have a voice and an opinion.