Final answer:
The quotation that best exemplifies social contract theory is the one that states governments derive their powers from the consent of the governed, which aligns with the principles articulated by philosophers like Locke and Rousseau.
Step-by-step explanation:
The quotation that most clearly exemplifies social contract theory is option 2, "That to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed."
This statement reflects the key principles of social contract theory, as articulated by philosophers such as John Locke and Jean-Jacques Rousseau, wherein a government's legitimacy comes from its people's consent and its principal function is to protect the inalienable rights of its citizens. If a government fails to protect these rights, the people have the authority to alter or abolish it and establish a new government that will ensure their security and well-being.