One more question about I-131 form

I'm renewing my AP at this moment. I have used an AP once in Feb 2008, and I'm planning to travel back to China during Chinese New Year next year. Currently, my status is H1B (just renewed to 2012 with my new job). I wonder what I should fill in at the "Class of Admission" area, "AOS" or "Temporary Worker".

Thank you so much to ANYONE who can answer my question! _;)

Best luck to everyone who is applying GC!_(*)