Seward’s Folly refers to the "<span>(C) United States’ purchase of Alaska," since this deal was made by William Seward, and was seen by many at the time as being a waste of money. </span>
The U.S. expanded due to them winning the war
The main way in which inventions such as the telescope and microscope changed the way people saw world is that the former invention allowed them to see into space, which gave a much better representation of Earth's place in the Universe--while the latter invention allowed people to see microorganisms and things like cells, which allowed them to better understand life on earth.
The railroad boosted the economic status of the USA the transportation of raw materials and manufactured good to and from industries became faster and easier after the completion of the railroad
The correct answer should be both a and b
While the imperialists had guns and weaponry like that, many African people still fought with spears, which often made it easy to conquer them. Of course, there were exceptions, especially when it comes to Britain, where they just couldn't defeat the locals. Their industry didn't exist and was undeveloped.