By the early 1900s, Germany had worsening relations with all of the following except "Austria-Hungary", since a wave of nationalism in Germany gave them the impression that Austria-Hungary was really a part of Germany anyway.
Answer:
Mutual defense alliances was a significant cause for starting World War I. Basically, what happened was all of the countries were somehow alliances with other countries. Conflict between different countries caused the allied countries to be involved which eventually led to World War I.
Explanation:
