user: Question: Which call sign has a frequency of FM 105.3?
Columns: ['Frequency', 'Call sign', 'Branding', 'Format', 'Owner']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['FM 91.5', 'CKBT-FM', 'The Beat', 'top 40', 'Corus Entertainment']
SQL:

assistant: SELECT "Call sign" FROM "Table" WHERE "Frequency" = 'FM 105.3';