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

### Instruction:
What is the lowest quantity of the 1b n2 type, which was retired in 1907-12?

### Inputs:
table_name: table, columns: ['Class', 'Quantity', 'Type', 'Delivered', 'K.B.Sts.B. Class', 'Retired']

### Response:
SELECT MIN Quantity FROM table WHERE Type = 1b n2 AND Retired = 1907-12