Which activity made the most money after world war i?

Even though both ww1 and ww2 were in many ways the same conflict with basically the same countries facing off against each other, the way each war started was significantly different. the question is how what were the differences on how they started

How did the new working class of the industrial revolution differ from the working classes of the earlier, farm based economy?

What did palestinian leader mahmoud abbas promise after succeeding yasir arafat in 2004?