The primary characteristic of a feudal society is the exchange of land for services.
The overlord will grant the vassal a land in exchange for the vassal's services. Services like fighting beside the lord in terms of war. Vassals have their own men and since the vassal is at the service of the overlord, his men is also at the service of the overlord.
The action which best illustrates checks and balances is (3) the House of Representatives Ethics Committee reviewing members' financial records. Checks and balances is a system where one part of government checks and regulates what another part of government is doing to make sure that they are doing everything rightfully and lawfully. This is often very present when their is a separation of powers and in a bicameral government.
History is a social science that studies past social and political events. As a discipline, it uses a methodology in order to study historical facts. Facts are objective for every Historian, but when Historians interpret the same facts often they arrive at different conclusions. That is because interpretation is highly subjective and the only way to interpret facts is through some specific perspective, a point of view or paradigm. When Historians interpret some period of History using a theoretical framework, they look at History like looking through glasses that enhance some factors in detriment of others. And that is inevitable when doing the historical interpretation.
Take, for example, Vladimir Lenin and the rise of the Soviet Union. According to Marxism, it was the forces of a social class, the workers, that rose against the imperial Russian state and the bourgeoisie that led to the creation of a Communist state. There are several historical documents that back this point of view. But according to Intentionalism, it was the powerful and attractive personality of Lenin and his talent for politics which led to the fall of the empire and the establishment of a new political system. Again, this is also very well-documented.
Of course, there can also be many other interpretations for this fact. For any historical event, there are many alternate interpretations, each of which looks at different -and many times contradicting- factors of History.
