If that's really a listbox, what you need to research is how to dynamically set the listbox rowsource based on a sql statement, or how to do that with a parameter query. A parameter query gets criteria for its fields based on either a) user input or b) from form controls. You would go with the form controls method if you choose the query approach.
Another method involves writing code for a button click event to set the listbox rowsource when you've finished choosing combo options.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.