Final answer:
Popular sovereignty entails a government's power deriving from the people's consent, making civic engagement key to ensuring that it reflects the public's will, as citizens exercise their authority through voting and political participation.
Step-by-step explanation:
The principle of popular sovereignty means that civic engagement is vitally important to keeping American democracy strong because it empowers the people to govern themselves (option c). Popular sovereignty is the idea that the power of the government comes from the consent of the governed. This means the right to vote and participate politically is essential in ensuring the government reflects the people's will. Civic engagement, such as voting, protesting, and campaigning, allows citizens to influence their leaders and shape government policy. Hence, participation through voting and other civic activities change those who are in powerful positions of authority, and this involvement allows democracy to serve the interests of its constituents effectively.