How to Add Row Number Column in Select query

Hello All ,

I have this query and i need to add Row Number Column i try this code but not correct ,

int count = 0;

var SourceIDS = (from main in db.RiskSources

join subCat in db.SubCategories on main.SubCategoryID equals subCat.ID

join description in db.Descriptions on main.DescriptionID equals description.ID

where Configrations.Any(a => a.sub_category_Id == main.SubCategoryID && a.category_Id == main.CategoryID)

select new

{

RiskSourceID = main.RiskSourceID,

No = ++count ,

status_record = "",

subCat_Name = subCat.Name,

description_Name = description.Name,

}).ToList();