I am building a form, and I have a multiselection checkbox choice control called Segments. It has about 30 options in it. Further down the form, I have a dropdown choice control. I want the dropdown options to populate based on the checked boxes from Segments. For example, if the user checks SegmentOption1, SegmentOption5, and SegmentOption23, I want the those three selections to be the only options in the dropdown further down the page. How do I make that happen?