user: Question: Who made the car that won the race on May 21?
Columns: ['Year', 'Date', 'Driver', 'Team', 'Manufacturer', 'Laps', 'Miles (km)', 'Race Time', 'Average Speed (mph)', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1969', 'July 6', 'Richard Petty', 'Petty Enterprises', 'Ford', '300', '300 (482.803)', '2:35:28', '115.772', 'Report']
SQL:

assistant: SELECT "Manufacturer" FROM "Table" WHERE "Date" = 'May 21';