Answer:
The excerpt from the text in which Keneddy most clearly acknowledges the viewpoint that no system of government is ideal is C. "Freedom has many difficulties and democracy is not perfect, but we have never had to put a wall up to keep our people in, to prevent them from leaving us."
Step-by-step explanation:
This excerpt conveys the idea that, although it may be not be flawless, democracy is the best option a society has to preserve its liberties. In fact, he exemplifies this idea by comparing the democratic system to the fascist system that ruled Germany during the Second World War.