Answer:
B
Step-by-step explanation:
The Treaty of Versailles was the treaty that officially ended WWI. Unfortunately, many of the premises of this document fell badly for Germany, and the leaders became quite embittered by that. They soon began to break some of the promises they made, but the League of Nations (precedent of the UN) made no real attempt to stop them. So, dictators began to rise, including Adolf Hitler, and build powerful armies.
Hope this helps!