user: Question: Who was the womens doubles when the mixed doubles is Jacco Arends Selena Piek?
Columns: ['Year', 'Mens singles', 'Womens singles', 'Mens doubles', 'Womens doubles', 'Mixed doubles']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1969.0, 'Flemming Delfs', 'Anne Berglund', 'Keit Arthur Ray Stevens', 'Joke van Beusekom Marjan Luesken', 'Gert Perneklo Karin Lindqvist']
SQL:

assistant: SELECT "Womens doubles" FROM "Table" WHERE "Mixed doubles" = 'Jacco Arends Selena Piek';