How to load data into dropdownlist using linq in 3 tier architecture?

I expect my dropdown to load in 3 tier architecture using linq concept.

In the user interface layer, I will use my function as

Datatable tbl=new DataTable();
tbl=loadDropDown("table name");


where, the function should return the result as table for Dropdown datasource

Please help me.

Thanks in Advance,
MOhan J