How do I print in grayscale on Canon Pixma MP280?

From my Macbook Pro (10.5.1), the print dialog has no grayscale option (screenshot below). I opened settings, and there is a color option in each Preset. The Presets are read-only. I guess I am supposed to click _Duplicate_ and edit a copy, but the _Duplicate_ button is disabled (screenshot at bottom), regardless of which of the three Presets is selected. How do I print in grayscale or black-and-white?