user: Question: When Roxanne and Daniel are the couple what is the highest rank?
Columns: ['Rank', 'Couple', 'Judges', 'Public', 'Total', 'Vote percentage', 'Result']
Types: ['real', 'text', 'real', 'real', 'real', 'text', 'text']
Sample row: [1.0, 'Ray and Maria', 10.0, 8.0, 18.0, '14.618%', 'Safe']
SQL:

assistant: SELECT MAX("Rank") FROM "Table" WHERE "Couple" = 'Roxanne and Daniel';