What do you see as the key factors that led to the Central Powers to sign the armistice that ended the fighting in November 1918?

Answer the following questions, each question should be 1000 words excluding quotations :
Q1)
Few historians have argued that World War I was monocausal, owing in part to the complex factors that shaped the events of the summer of 1914. identify and explain what you see as the three key factors (from the list) that brought on the war. (Nationalism, the alliance system, imperialism, militarism, the arms race, Social Darwinism)

Q2)

What do you see as the key factors that led to the Central Powers to sign the armistice that ended the fighting in November 1918?