After the Archduke’s assassination, all the great powers of Europe began declaring war on one another. This is an example of which idea: A. Alliance systems
B. Militarism
C. Imperialism
D. Nationalism

Historians have recently discovered a historical journal published in the early twentieth century. the journal contains facts based on original sources about the downfall of the early byzantium empire. historians consider this long-lost journal to be a breakthrough in their understanding of the byzantium empire. based on this information, the journal is a source.