Database: beer_factory
Question: Which brewery does the most purchased root beer in 2016 belong to?
SQL: SELECT T2.BreweryName FROM rootbeer AS T1 INNER JOIN rootbeerbrand AS T2 ON T1.BrandID = T2.BrandID WHERE T1.PurchaseDate BETWEEN '2016-01-01' AND '2016-12-31' GROUP BY T2.BrandID ORDER BY COUNT(T1.BrandID) DESC LIMIT 1