The correct answer is C) People always say that I'm untrustworthy, but I really don't see why.
If you were writing a story in which you mean to make the reader doubt the first-person narrator's reliability, the choice that would make the best opening sentence would be "People always say that I'm untrustworthy, but I really don't see why."
This is the best statement to start with because it is implying that the narrator itself is posing the affirmation that people do not rely on it and it doesn't know why. So from the very beginning of the story, the reader is doubtful of the narrator's credibility for the way it started the story. So in the next pages, readers could be doubtful of the narrator is saying.
