The res ipsa loquitur doctrine allows inference of negligence when:

The correct answer to the question "The res ipsa loquitur doctrine allows inference of negligence when:" is Option B: The accident is of a kind that normally does not occur without negligence and the instrumentality was under defendant exclusive control.

The other options — A) The plaintiff saw the defendant act, C) There are witnesses, D) The defendant confesses — are incorrect for this BAR Exam Prep question. As explained above: Res ipsa loquitur: (1) the event normally doesn't occur without negligence, (2) instrumentality under defendant exclusive control, (3) plaintiff did not contribute. Creates inference of negligence.