In order to rely upon the defense of contributory negligence, what must a defendant prove? Multiple Choice That the plaintiff's conduct fell below the standard of care needed to prevent unreasonable risk of harm and also that the plaintiff's failure was a contributing cause to the plaintiff's injuries. Only that the plaintiff's conduct fell below the standard of care needed to prevent unreasonable risk of harm. That the plaintiff's conduct fell below the standard of care needed to prevent unreasonable risk of harm that the plaintiff's failure was a contributing cause to the plaintiff's injuries, and also that the plaintiff failed to abide by the last-clear-chance doctrine Only that the plaintiff violated the last-clear-chance doctrine. Only that a failure of the plaintiff was a contributing cause to the plaintiff's injury