Since we are talking about the American romantic period, I'd say that what the archetype of the devil usually symbolizes in the literature of that era is C. the romantics' fascination with the supernatural.
They were crazy about the dark and mysterious creatures, so maybe that is the correct answer.
In "Civil Disobedience," Thoreau championed the idea that if a government is not going to improve itself, then it is the duty of the people to refuse to support it. This paved the way for non-violent protests, such as those led by Gandhi and Martin Luther King, Jr.