Voted B - most are self-deluded.
I would have gone for a mix of B through F, as I think some may employ some sort of doublethink and know at some level that their "powers" are not real. Religious people experience this too, and may have periods of doubt followed by returning to the fold and believing stronger than ever. When you have followers depending on you and idolizing you, affirmation is easy to come by - and that may also create a pressure to perform.
I think, judging by the justifications I've heard from ordinary believers in psychics, astrology etc., that it is possible a psychic or diviner can maintain their beliefs through the ordinary fallacies: Confirmation bias, positive feedback (I feel so much better after the reading!), emotional response / pseudo-religious experiences. Believers, in my experience, simply use a different tool set for determining truth values - if it feels right, it must be true. That, maybe coupled with a general distrust of authority and the scientific establishment, makes it easy for the believer to see themselves as some sort of rebel that has a valuable mystic understanding of the world.
Sorry for rambling. Just have to add that even though I think a lot of it is genuine self-delusion and good intentions, this doesn't absolve the psychic from responsibility; they are playing with fire by telling people who are trusting them what is in essence unsubstantiated guesswork. They may not realize it, but they are hurting people.