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

### Instruction:
Marcell Jansen with a transfer window of summer, and of transfer as type is from what nation?

### Inputs:
table_name: table, columns: ['Nat.', 'Name', 'Type', 'Transfer window', 'Transfer fee']

### Response:
SELECT Nat. FROM table WHERE Transfer window = summer AND Type = transfer AND Name = marcell jansen