True, the narrator can be all of those things. Some examples include the following:
Major Character who's the narrator: Hazel Grace Lancaster in The Fault in Our Stars
Minor Character who's the narrator: Nick Carraway in The Great Gatsby
Protagonist: Esther in Sylvia Plath's The Bell Jar (narrated in 1st Person POV)
Antagonist: Amy Dunne in Gone Girl by Gillian Flynn
A novel that romantically portrays the ideals of country life.
Have you ever had a friend over that just trashed your place and left...? Well that's what we are basically doing to the enhabitants of our environment!
It would be C. context. Because if you know the context of the technical term you can almost always deduce or induce what it means, it wouldn't be connotation because that means implied meaning; complexity doesn't show you the meaning it just makes it harder to understand and corroboration doesn't fit in the context of the sentence.