Answer:
A. Nations responded to threats to their allies by mobilizing their militaries.
Explanation:
The outbreak of World War I was greatly due to the system of alliances made between the powerful European countries of the time. This system obligated a country to go to war if its ally was being threatened or attacked.
There were 2 main alliances on the eve of WWI, the Triple Alliance between Germany, Austria-Hungary, and Italy, and the Triple Entente between France, Britain, and Russia.
Once the "powder keg was ignited" all of these countries began mobilizing their armies in order to support and uphold their alliances.
I believe the answer is: Started children bureau and supported Mann Elkins act
The children bureau was established to prevent children abuse and other form of mistreatments, which contribute a lot in the elimination of child labor and the mann elkins act was enacted in order to create governemnt regulaitons that prevented unfair business practice.
B. The consent of the governed
C. The self-evident rights of life, liberty, and the pursuit of happiness
D. The right of the people to institute a new government