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

### Instruction:
what is the fuel propulsion where the fleet series (quantity) is 310-329 (20)?

### Inputs:
table_name: table, columns: ['Order Year', 'Manufacturer', 'Model', 'Fleet Series (Quantity)', 'Powertrain (Engine/Transmission)', 'Fuel Propulsion']

### Response:
SELECT Fuel Propulsion FROM table WHERE Fleet Series (Quantity) = 310-329 (20)