There were actually four HUGE causes for WW1, treaties and alliances brought many countries into war, the imperialism of some countries scared other countries, and they were "defending" themselves, there was a lot of weapons stocking, and countries were creating gigantic armies, and that threatened other countries, and then we have plain old nationalism.
The answer may be "tobacco".
One of the reasons why stock bought on margin is considered a risky investment is because "Investors purchased the stocks with little cash down," meaning that they had to borrow the remained of the money.
It wont let me answer, I’ll put my answer in the comments
