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

### Instruction:
Which category earlier than 2006 has Bart Brentjens as rider 2?

### Inputs:
table_name: table, columns: ['Date', 'Category', 'Team', 'Rider 1', 'Rider 2']

### Response:
SELECT Category FROM table WHERE Date < 2006 AND Rider 2 = bart brentjens