D is the answer general anthony
Many knights were professional warriors who served in the lord's army. ... In return, the lord provided the knight with lodging, food, armor, weapons, horses and money. Peasants, or serfs, farmed the land and provided the vassal or lord with wealth in the form of food and products.
The answer is C.
After the assassination Austro-Hungary sent an ultimatum to Serbia to investigate the assassination in Serbia, but Serbia declined the ultimatum, so Austro-Hungary declared war to Serbia. Then Russia declared war to Austro-Hungary and Germany declared war to Russia. Then the Ottoman Empire joined Germany and Austro-Hungary and they created an alliance and some other countries joined as well. After that, Great Britain, Russia and France created an alliance as well, and some other countries also joined their alliance. That's a short summary of how the WW1 started.
The modern era came about in the French revolution
