A -- Reads the last chapter first. Of fiction? No, no, no, no, no! There was a reading promotion ad on the radio a while back in which LeVar Burton confessed that sometimes he liked to peek at the ending. I cringed when I heard it. Nothing would be more likely to make me want to quit reading.
B -- Decides to DNF within the first two chapters. I had to look up "DNF", but suppose that applies to me. With rare exceptions if a book doesn't interest me within two chapters, then it's lost its chance. (After all, there are millions of books I'll never get a chance to read, and it got a better chance than most.) Not that this happens often, as I usually pick books I'll like.
B and H (Has a TBR mountain but still buys or borrows more books) probably apply to me better than the other choices, though. I don't buy many books nowadays, but often borrow or find free copies on the internet of books that appeal to me more at the moment than any I'd already planned on reading.