Find the brand Id of the root beer which has the most number of customers who gave 1-star ratings.
most number of customers who gave 1-star ratings refers to MAX(COUNT(StarRating = 1)); 1-star ratings refers to StarRating = 1;
SELECT BrandID FROM rootbeerreview WHERE StarRating = 1 GROUP BY BrandID ORDER BY COUNT(BrandID) DESC LIMIT 1