Creating Listbox dynamically based on dropdown value

Hi Friends,

i need the coding for the below requirement as soon as possible.

in asp.net,  i created 1 dropdown list inside items are like lkg,ukg and 1st standard etc... 

 when i select the lkg from the dropdown list it should display 1 listbox with values, when i select ukg it should create 2 listboxes with values, so like this dynamically the listbox should increase. i need a output like this.

so please give me the full codings for that.


Thanks and Regards,
Ramachandran