user: Question: What denominations are the stamps with themes Opera, Léopold Simoneau and Pierrette Alarie?
Columns: ['Date of Issue', 'Theme', 'Denomination', 'Design', 'Illustration', 'Printing Process', 'Paper Type', 'First Day Cover Cancellation']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['3 April 2006', 'Birthday', '51 cents', 'Designwerke Inc., Andrew Perro', 'Designwerke Inc., Andrew Perro', 'Lithography in 8 colours', 'Tullis Russell Coatings', 'Ottawa, Ontario']
SQL:

assistant: SELECT "Denomination" FROM "Table" WHERE "Theme" = 'Opera, Léopold Simoneau and Pierrette Alarie';