It was Carl O. Sauer who did
A and E are the correct answers. Bulgaria and Albania are by Macedonia, meaning its by the old Yugoslavia, witch also means its more south of Europe. Croatia is part of what was Yugoslavia, making it too far south.
Watershed is probabley the answer you are looking for
The correct answer is - D) Jewish immigrants in Poland who fled to the United States to escape religious persecution and seek safety and new opportunities.
The push factors are the factors that make the people move away from one place to another. They are negative factors, and can be economical, political, because of safety reasons etc.
The Jews that fled Poland in order to feel safe and get new opportunities in life in the United States, based on the religious and ethnic persecution, is a nice example of a push factor. In this case we have a push factor motivated on religious and ethnic hatred, which of course will make the people of the persecuted group feel unsafe, threatened, so they will try to move away if possible because their lives are in danger.