user: Question: Who was the constructor of the Officine Alfieri Maserati that was driven by Sergio Mantovani?
Columns: ['Entrant', 'Constructor', 'Chassis', 'Tyre', 'Driver', 'Rounds']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Officine Alfieri Maserati', 'Maserati', '250F A6GCM', 'P', 'Juan Manuel Fangio', '1, 3']
SQL:

assistant: SELECT "Constructor" FROM "Table" WHERE "Entrant" = 'Officine Alfieri Maserati' AND "Driver" = 'Sergio Mantovani';