I believe the right answer is B. The invention of gunpowder! Gunpowder was invented in China :)
Answer: The Middle Colonies were able to grow large quantities of crops because the farmers used slaves to help grow their crops without spending money on wages. ... Cash crops affected the development of slavery because the more valuable the crops were, the more slaves were needed for the colonies to make more money.
Well, the most important effect of nationalism in Europe in 1900s was the World Wars. Citizens of many countries were unhappy with the economy and the way things were in their states. This, along to the critical approach towards other nations and the growing national socialism led to the outbreak of military conflicts, pogroms, and eventually the holocaust and facism during the World War II. One important thing is that were talking here about very extreme nationalism.
Hitler invaded Poland in 1939 which led the the British and French declaration of war on Germany.
