Need Help ? Does ASP.Net have any "AUTO EXPAND " property

I have used the AUTOEXPAND property in the Dropdown box in the MS access

I need to Implement almost a similar feature in asp.net

a single dropdownbox is avialable

once data is selected , a new dropdownbox automatically appears below . 

Do ASP.Net has anything similar to AUTOEXPAND property

Any help is really appreciated

thanks
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