Which is a system of leaders who carry out the work of government?

a. aristocracy
b. bureaucracy
c. democracy

I think the answer to this is C

c: makes the most sense, An aristocracy the highest class in certain societies, especially those holding hereditary titles or offices. Bureaucracy is a system of government in which most of the important decisions are made by state officials rather than by elected representatives and a democracy a system of government by the whole population or all the eligible members of a state, typically through elected representatives.

Primary sources are usually  more accurate and are written by someone who experienced it or witnessed it. secondary sources are those who heard of it after the fact that can lose details and or twist the event in a light that benefits them.