The correct option is B.
Jackie could not believe that Nora can act so religiously. He knows her sister to be a loud person and he considered her to be a worst sinner than himself, so he find it quite unbelievable that her confession only took a few seconds and she was acting as if she was a saint. Jackie considered his sister to be a hypocrite.
Than, because then is used in chronological order. than is used to introduce second elements in comparisons.
