Final answer:
The Enlightenment idea that influenced the Declaration of Independence was the social contract theory, emphasizing that people have natural rights such as life, liberty, and the pursuit of happiness.
Step-by-step explanation:
An idea from the Enlightenment that influenced the Declaration of Independence was (Option:1) the social contract. This concept, predominantly formulated by John Locke, proposed that individuals have fundamental natural rights, including life, liberty, and property, which Thomas Jefferson famously referred to as the 'pursuit of happiness' in the Declaration.
These principles expressed the notion that if a government fails to protect these rights, the people have the authority to alter or abolish it. Numerous Enlightenment figures, such as Montesquieu, also proposed ideas about government structure that influenced the Founding Fathers, such as the separation of powers, but it was the social contract that directly impacted the rationale for American independence.