The treaty of versailles was unfair towards Germany, so that would probably the spark on the western front.
Hitler prepared rather long for an all out war, he took parts of former germany back in peace. Later the USSR (union of Russia and a lot of other countries) took Poland together. (they had a non-attacking treaty). With attacking poland, France and the UK declared war and Germany took over France, Belgium and Holland almost instantly
The President is impeached for the violation of the Constitution.
They spread knowledge of medicine, mathematics, and other sciences. The hindu-arabic mathematical numerals 0-9 is still used today.
For the first one it’s C for the second it’s it would be B
Economic - several writers have noted the role of monastics as entrepreneurs.
Social - any good text about medieval monasticism can give you plenty of specific examples of this.
Missionary - some orders were more active in this regard than others.
Cultural - this is perhaps the best known of the work of medieval religious orders and included the creation of the great illuminated manuscripts of the age.