APEX

I need to create several select lists in a form that can each populate the same field in a table, but obviously need for the select lists in the form to be mutually exclusive so that the user can only enter data into one of them.

There is also a field on the form displayed as a radiogroup, and I would like for the user's selection on this radiogroup to dictate which one of these multiple select lists they use to enter this data.

Before I do any of this, however, I guess my first question is, how do I create multiple text entry fields on a form for just a single field in the table?