displaying data field in a label using jquery

Question

I have three dropdowns, Acaademic year,Class,Section,  based upon the selections in these three dropdowns

 

i need display the corresponding roll no of the student in a label using jquery in mvc.

 

there are different master table for academic year,class,section,set roll no with ids, eg:Roll_Id

 

plz guide me.

 

 

thanks 

Rizwan