Cascading DropDown List Menu

I have three drop down list menu's that are generated from a database. However, I would like someone to change them into a cascading list menu. For example: User chooses selection from dropdown A Dropdown B available options depend on selection from A Dropdown C available options depend on selection from A & B I have attached the PHP code for the menu's which work fine without cascading implemented. The outcome from dropdown C is the following URL: [login to view URL][Class_ref] You can see how the menu's are displayed on the page here: <[login to view URL]$sitepreview/[login to view URL]> (You will need to copy and paste this url into your browser) This is required urgently. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform PHP/MySQL/Javascript (?)/HTML