A, firearms. Whitney also invented the cotton gin earlier, but his work on interchangeable parts began with firearms
Answer: Horizontal integration is important because it grows the company in size, increases product differentiation, achieves economies of scale, reduces competition and can access new markets. When many firms pursue this strategy in the same industry, it leads to industry consolidation which makes the companies stronger and more solid and even monopoly- which isn't the best for consumers but is really good for the sellers.
Germany needed weapons for the war so they employed more and more people. At one point in time they even employed Children, when the war was becoming troublesome for them. They would also have labor camps where prisoners would have to work and make things for Germans, but they were more concentration camps than labor camps and those who couldn't work were executed. It was overseen by the government.
It was to the American people so that Pearl Harbor is never forgotten
Industrial Production Increased