user: Question: How many rounds was the bout against Bobby Rehman?
Columns: ['Res.', 'Record', 'Opponent', 'Method', 'Event', 'Round', 'Time', 'Location']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Win', '30-13', 'Silmar Nunes', 'Decision (unanimous)', 'Iron Fight Combat 4', 3.0, '5:00', 'Parana , Brazil']
SQL:

assistant: SELECT "Round" FROM "Table" WHERE "Opponent" = 'Bobby Rehman';