Populate datagridview column combobox datasource

Question

Hello:

 

I would like the correct C# syntax to populate datagridview column comboboxes. Each column will look at a query (Entity Framework 6), converted to a list, and would make those values the correct ones to choose from. There should also be a blank for a default.

 

Currently, I have this code.

DataTable dt_Employee = timeDataSet.Tables["Employee"];
DataTable dt_TimeData = timeDataSet.Tables["TimeData"];
DataTable dt_Activity = timeDataSet.Tables["Activity"];
DataTable dt_Jobs = timeDataSet.Tables["Jobs"];
var qryProjectNumbers = from a in dt_Jobs.AsEnumerable()
orderby a.Field<String>("ProjectNumber")
where (a.Field<String>("ProjectNumber") != null)
select a.Field<String>("ProjectNumber");
var lstProjectNumbers = qryProjectNumbers.Distinct().ToList();
var qryActivity = from a in dt_Jobs.AsEnumerable()
orderby a.Field<String>("Activity")
where (a.Field<String>("Activity") != null)
select a.Field<String>("Activity");
var lstActivity = qryActivity.Distinct().ToList();
// How do I add combobox columns?
dgvTime.Controls.OfType<DataGridViewComboBoxColumn>().ElementAt(iProjectNo).DataSource = lstProjectNumbers;
dgvTime.Controls.OfType<DataGridViewComboBoxColumn>().ElementAt(iActivity).DataSource = lstActivity;
this.timeDataTableAdapter1.Fill(this.timeDataSet.TimeData);

Thank you.