I believe it's quadratic, as quadratic matches the second time while linear matches the first time you find the differences.
A) Railroads
Railroads helped to transport resources, manufactured goods, and people all over North America, greatly speeding up the industrialization of the entire continent, especially the United States. Where as industrialization previously existed mostly along coastal cities where materials could quickly be shipped to and from industrial centers, the entire continent was now much more easily accessible for this.
Answer:
Germany
World War II began in Europe on September 1, 1939, when Germany invaded Poland. Great Britain and France responded by declaring war on Germany on September 3. The war between the U.S.S.R. and Germany began on June 22, 1941, with the German invasion of the Soviet Union.
Explanation:
