The correct answer is - pull factors.
The increased freedom and much more employment opportunities in the United States can be considered as pull factors. They can be considered as pull factors because they are big reasons why people from all around the world got attracted to the idea of migrating to the United States, as they saw a nice chance to prosper and have a better life. Most of the countries were still struggling with the freedom issues, and the employment opportunities were either very limited, or badly payed, so no wonder that pople wanted to move in the United States.
Hello. You did not post the announcements that the question refers to, but I can help you, since the announcements that reflected European views at the time of imperialism, generally displayed obvious ideas about the purity and superiority of the white man and the idea that colonies are dirty places without civilization.
The idea of purity and superiority is related to the idea of the "white man's burden", which was a concept that stated that it was a duty (given by God) to Europeans to "clean up", take Christianity and dominate regions with inferior people , in this case, non-white people who lived in other countries, who were considered unclean and therefore needed to be purified by whites.
In this way, Europeans used a strong racist bias to dominate and enslave peoples of other ethnicities, promoting imperialism while claiming that this was the role that God had assigned to whites in this world.
The Correct Answer Would Be:
~ It was not known whether all states would respond to an attack on one state.
