Dependent Dropdown List/Menus is very useful, it will give you ability to select data that related together, in the very popular example when the visitor selecting: country he must search for the related city, then he search for the related state, too hard, specially if you have a database holding the whole world countries, cities, and states.
So what is the alternative? good question!
Is it possible when select a country the city and state automatically selected that realted to this country? another good question!
Yes you can, using the advanced form controls that Adobe Developer Toolbox offers --> you can.