how to bind gridview value to dropdownlist in popup

i have column name BenefitDeductType in gridview and dropdown in model popup

i need the selectedtext of dropdown =gridview.BenefitDeductType in rowcommand

ddlBenefitsAndDeductionsType.SelectedValue = Select.Cells[(int)GridColumns.BenefitDeductType].Text;

int RowIndex = Convert.ToInt32(e.CommandArgument);

GridViewRow Select=grdBenefitsAndDeducts.Rows[RowIndex];

txtBenifitsandDeducts.Text=((LinkButton)Select.Cells[(int)GridColumns.TypeName].Controls[0]).Text;

ddlBenefitsAndDeductionsType.Text = Select.Cells[(int)GridColumns.TypeName].Text;

string Isbasic = grdBenefitsAndDeducts.DataKeys[RowIndex].Values["IsBasic"].ToString();

chkIsBasic0.Checked = (Isbasic == "True") ? true : false;

Button1_ModalPopupExtender.Show();