Answer:
It was the Treaty of Versailles and totalitarianism.
Step-by-step explanation:
Those two things highly impacted the contributions to WW2. Long story short, when a small, angry man with a silly mustache said to all of the people in Germany that he could, and would fix everything, they were all really happy and then voted for him. But then, as he grew popular, he then started to blame everything on the Jews and how it was all of their fault everything had happend. So, that's pretty much how WW2 started.
Hope this helps you!