user: Question: Which Round has a Ranking of 2008 WTA Tour?
Columns: ['Player', 'Ranking', 'Event', 'Surface', 'Round', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['2008 WTA Tour', '2008 WTA Tour', '2008 WTA Tour', '2008 WTA Tour', '2008 WTA Tour', '2008 WTA Tour']
SQL:

assistant: SELECT "Round" FROM "Table" WHERE "Ranking" = '2008 WTA Tour';