Dropdown lists synchronized

Hi all
is it possible (in visualization) to have two syncronized dropdown lists based on queries?
For example: list A shows some strings from a query. When I select an item, list B shows some results by query based on list A choice.

Not directly. The query that powers a Query Based Dropdown List Parameter cannot itself use parameters. But you can do the same thing with a Query Parameter and a Query Filter. Use the the parameter for dropdown A, and the filter for field B.