user: Question: Which class has a rank of 5th?
Columns: ['Year', 'Class', 'Team', 'Points', 'Rank', 'Wins']
Types: ['real', 'text', 'text', 'real', 'text', 'real']
Sample row: [1972.0, '125cc', 'Aermacchi', 2.0, '38th', 0.0]
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "Rank" = '5th';