I'm not entirely sure but I'd imagine they're considered holistically? If you've performed well on two of the questions, unless the competition was
really fierce, it would seem harsh to penalise you if one answer was weaker. Stuttering and repetition is normal (if expected) in a VI because they're unnatural. As long as there was substance to your answer and it was structured well, you probably did better than you think
However, I don't think your application comes into it at this stage. You've got through the VI based on the strength of your application so believe the VI is determined on its own merit. Please correct me if I'm wrong on this though!