The Three Emperors League in 1872 was between Alexander II of Russia, William I of Prussia, and Francis Joseph of Austria-Hungary.
The agreement was renewed in 1881 with Alexander III replacing Alexander II of Russia. William I and Francis Joseph remained as signatories.
The congress was very powerful at the time and needed to be put in line. The two branches were created to control it. The remaining two branches were not specifically enumerated as thoroughly because they were still weak at the time and their power developed over time.
The answer is C. Delegated Powers
Delegated powers (also known as Enumerated powers) are powers which were given to the federal government by the constitution. These powers ONLY allow the FEDERAL government to do these things. They cannot be taken up by the states. Hope this helps;)