Answer : Amendment 4
My teacher gave this to me and it helped me it the past days I hope this can help you.
More Americans were able to buy homes after the WWII because of the purchasing power of the American Dollar. In order for the country to experience a drastic economic change, it had to change its policies about taxes, cost of living, and personal wages of its people. So during that time period, people had a lot of money and decided to change their old ways of living in the city and moving into the suburbs to buy a lot and build their own houses there. They found that life was more peaceful and quaint as compared to the city life that's why there was a boom in suburban life after the WW.
The factors that made it difficult for Eastern Europe to improve its water quality were outdated sewer systems, raw water quality, worn-out water utilities and unskilled employees. So we can say that four options given in the question fits the bill perfectly. These basic infrastructural reasons were responsible for being a hurdle towards improving the water quality. <span />
The Civil War started because of uncompromising differences between the free and slave states over the power of the national government to prohibit slavery in the territories that had not yet become. I believe so.