B was the answer my teacher gave me
Answer:
Economic Factors Most of the studies indicate that migration is primarily motivated by economic factors. In developing countries, low agricultural income, agricultural unemployment and underemployment are considered basic factors pushing the migrants towards developed area with greater job opportunities
Explanation:
The Germans sank a British ship which had American passengers. This was the first step. After this due to the unrestricted submarine warfare more US ships were sunk by German U-boats.
I thank that it is the Indian Removal Act.
