user: Question: Which Frequency MHz is the highest one that has a Call sign of K241AN?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['K202BP', 88.3, 'Bellaire, Smith County, Kansas', 78.0, 'D', 'FCC']
SQL:

assistant: SELECT MAX("Frequency MHz") FROM "Table" WHERE "Call sign" = 'K241AN';