2- East Germany and West Germany
West-the USA, Britain and France
East- Soviet Union
I believe it's B) freezing and thawing of water beneath the soil
Urbanization caused many people to cluster into large cities. When a city was forming, many jobs began to open. People would leave their unstable farming, trading, fishing etc.. jobs in the rural areas for a more secure factory, office, business job opportunity in the city. This means that the population is distributed unevenly across the US, with the majority of people living in urban areas.
