Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What was the mens open when the mens u20 was  Qld Country Rustlers def Southern Suns?

### Inputs:
table_name: table, columns: ['Year', 'Mens Open', 'Womens Open', 'Mixed Open', 'Mens u20', 'Womens u20', 'Senior Mixed', 'Mens 30', 'Womens 30', 'Mens 35', 'Womens 35', 'Mens 40', 'Womens 40', 'Mens 45', 'Mens 50']

### Response:
SELECT Mens Open FROM table WHERE Mens u20 = Qld Country Rustlers def Southern Suns