The correct answer is He instituted a presidential cabinet.
Washington created a cabinet in order to help in making decisions for the country. At this time, Washington only had 4 cabinet members. This included Thomas Jefferson (Secretary of State), Alexander Hamilton (Secretary of Treasury), Henry Knox (Secretary of War), Edmund Randolph (Attorney General).
Each of these men were well versed in the areas they advised Washington in. For example, Jefferson was an expert in foreign affairs. This is why he was appointed the Secretary of State, as this role is based around the ability to make treaties/work with other countries.
"C. was overthrown by invading Mongol tribes in A.D. 1279" would be the best phrase describing China's Song Dynasty, but this was of course not always the case.
