The trend toward nationalism, militarism and imperialism lead to the start of World War I because Nations became more competitive and were willing to use force to further their growth.
The international war was regarded as one of the great watersheds of 20th-century geopolitical history because it led to the fall of great imperial dynasties in Germany, Russia, Austria-Hungary, and Turkey as well as resulted in the Bolshevik Revolution in Russia, destabilized European society and laid the groundwork for World War II.
As the main cause of World War I was narrowed down to nationalism, militarism and imperialism, this was because Nations became more competitive and were willing to use force to further their growth. Therefore, the Option D is correct.
Read more about World War I
brainly.com/question/446364
#SPJ1