"klug felt at home with dirt and drunkenness and , as far as he could remember , he had never been exactly sure of his location . so what ? there was something troubling klug ; but he did n't like to recall what it was . in fact , he was determined to be as unsure as possible about what it was that troubled him . it was clearly wrong , he mused , that he should be _ ..." What is the word in the blank space (_)? The answer is
troubled