Hi Bruce,
This forum is specific to Designer, which comes with Acrobat Pro 9. It will be easier to create this type of functionality in Designer (compared to achieving it in Acrobat).
Designer creates XFA Forms, which are wrapped in a PDF. The user doesn't see any difference: eg they see a PDF which will open in Acrobat/Reader. However for user with Reader to be able to save the data they input, the form must be reader Enabled. This is a topic in itself and there are many discussions on the forums - just try a quick search.
Now to the question...
Yes, you can achieve this with some script. Basically you would need script in the preOpen event of the Business sub-category, which would look back at the selection in the Business category. Based on this value, the script would populate the sub-category with appropriate items.
There is an example here: http://assure.ly/jcTahK.
Hope that helps,
Niall