Answer:
The answers are A, B, and A
Explanation:
3D printing uses computer-aided design (CAD) to create three-dimensional objects through a layering method. Sometimes referred to as additive manufacturing, 3D printing involves layering materials, like plastics, composites or bio-materials to create objects that range in shape, size, rigidity and color.
I think your question means how did the discovery of gold contribute to the creation of the transcontinental railroad. There had been some movements toward westward settlement in the 1840s, but that trend accelerated dramatically with the discovery of gold in California. James Marshall's finding of gold at Sutter's Mill in California in 1848 led to a "gold rush" in the decade that followed, with 1849 seeing a huge influx of people to California. (Thus we refer to the '49ers.) The swift settlement of California added incentive to build a transcontinental railway. The Pacific Railroad Act of 1862 established the charter for doing that. The First Transcontinental Railroad was completed in 1869.
1) ariel spying over Cuba produced pictures that showed missile silos being built in Cuba. The design of the silos made it clear they were designed for missiles, and it made no sense for Cuba to put in anything less than nuclear missiles there. Missiles they could not build themselves, so had to come from the Soviet Union.
2) Only minutes. A launch from the Soviet Union to the US only takes about 20 minutes. Depending on the range of the missiles put into the silos, warning time would have been anywhere from 3-10 minutes. Not enough time to verify that it was a launch, and not a detection system malfunction, forcing America to launch immediately, or risk losing its capacity to strike back.
3) A direct attack or invasion of Cuba would have forced the Soviet Union to respond in kind. The USSR simply could not abandon Cuba, without losing all credibility among its allies and vassal states. So they would likely have struck back at the US, probably in Europe. This would have dangerously escalated the tensions, and increased the probability of nuclear war. Other officials believed that a quick,determined strike would not only eliminate the immediate threat of missiles in Cuba, but possibly overthrow the regime and force the USSR to accept the situation. The idea of a naval blockade was a compromise position. A threat of force, but one that allowed the USSR to back off. After all, so long as the missiles were not put into the silos, they were no threat.
