It was mainly developments in the "steel" industry that made important contributions to improvements in the transportation system in the United States during this time, since the major advancement in transportation was in the railroads, which were made from steel.
B) computer, because the space program required equipment that could perform very complicated calculations.
Answer:
The Silk Road and other trade routes had become too dangerous, expensive and time consuming
Explanation:
Trade routes to Asia and the Middle East had become very dangerous for Europeans because non-friendly empires like Ottoman Empire and the Persian Empire were the middlemen between Europe and Asia.
For this reason, Europeans were pushed to explore alternative trade routes to Asia. In fact, Columbus idea was to sail west to find a new route to Asia, he never expected to land on a whole new continent.
Andrew Johnson Wrote his own Reconstruction plan after becoming president
