Answer:
Aircraft - The air force became one of the most important parts of the military during World War II. Whoever had control of the air, often won the battle on the ground. Radar - Radar was a new technology developed right before the war. It used radio waves to detect enemy aircraft.
Explanation:
If the change is the Industrial Revolution:
transcontinental railroad: helped to transport goods and get across the country
US army: helped to protect the US and make sure no one is going to break the new amendments
Discovery of resources in western land: Allowed the US to be able to expand and people would be able to live, could also give the US more money
In the late 1800s, the growth of the railroad system led Midwestern cities such as Minneapolis and Cleveland to become industrial centers.
They were folloing heards of food during the Ice Age, so the answer is C.
