Question: Among the "Mountain-500 Black" product types, which type was purchased the most?
SQL: SELECT T1.Name FROM Products AS T1 INNER JOIN Sales AS T2 ON T1.ProductID = T2.ProductID WHERE T1.Name LIKE 'Mountain-500 Black%' GROUP BY T2.Quantity, T1.Name ORDER BY SUM(T2.Quantity) DESC LIMIT 1