Building techniques improved, iron became more common, and hydraulics were used to dig riverbeds deeper. So less floods happened that destroyed farms and endangered lives.
Answer:
B
The North Atlantic Treaty Organization was created in 1949 by the United States, Canada, and several Western European nations to provide collective security against the Soviet Union. NATO was the first peacetime military alliance the United States entered into outside of the Western Hemisphere
The United Nations has only four purposes stated in the UN Charter of 1945. These purposes focus mainly on the maintenance of world peace and security, on the harmonious relationship among nations, as well as on having cooperation in eliminating international problems and issues, and above all, be the center on achieving the first three purposes.
