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

### Instruction:
Which permanent account has registration of invite-only and userpics free of unknown?

### Inputs:
table_name: table, columns: ['Name', 'Year Began', 'Registration', 'Userpics Free', 'Userpics Paid', 'Monthly Cost for Paid Account', 'Yearly Cost for Paid Account', 'Permanent Account']

### Response:
SELECT Permanent Account FROM table WHERE Userpics Free = unknown AND Registration = invite-only