The current U.S. government is an example of a b) representative democracy. A representative democracy is defined is a style of government which is founded on the principle of elected officials representing a group of people. All modern western-style democracies actually fit under the term "representative democracy."
One reason Renaissance art looks more lifelike than Medieval art is that it uses classical influences. Rather than being bogged down by religious dogma artists were free to explore the human and the secular through their art which led to a rebirth of classical methods of creating art.
The primary check the president has on Congress is the ability to veto legislation. The president can also choose to implement legislation in a manner Congress did not intend. Executive orders also give the president significant power.
