user: Question: Which class has a frequency of 91.9 FM?
Columns: ['City of license', 'Identifier', 'Frequency', 'Power', 'Class', 'RECNet']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Brockville', 'CBOB-FM', '91.9 FM', '1,080 s watt', 'A', 'Query']
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "Frequency" = '91.9 FM';