The mass production of what building material made it possible to build skyscrapers in the wake of the second industrial revolution?
steel
brick
clay
wood

Steel.  During the industrial revolution, steel had a major increase in production.  A way to remember this is to remember the man Carnegie Steel who ran a monopoly that controlled the steel industry during the Industrial Revolution.

The bomb should have been used on japan: sense of revenge.. and to finish the war as japan wasn't ready to.the bomb shouldn't have been used on japan: killed many people in that city and unjust