<div id="ManageAddressPage" runat="server">
        <asp:Repeater ID="Repeater1" runat="server">
     
    <ItemTemplate>
         <div id="EditAddressPage" style="border: solid 1px LightGray;background-color:#f5faff">
        <div style="padding:15px">
                <asp:Label ID="lblAddressID" runat="server" Text='<%# Eval("AddressID") %>' Visible = "false" />
             <asp:RadioButton ID="RadioButton" runat="server"  Onclick="javascript:singleselection(this.id)" ></asp:RadioButton>
            <asp:Label ID="lblContactName" style="margin-right:15px" runat="server" Text='<%# Eval("Name") %>' />
                <asp:Label ID="lblCountry" runat="server" Text='<%# Eval("PhoneNumber") %>' />
            
             </div>

             <div style="margin-left:10px;width:90%;margin-bottom:20px;">
            
                 <asp:Label ID="lbladdress" runat="server" Text='<%# Eval("Address") %>' />
                
             
              
        </div>
             </div>
    </ItemTemplate>
    
       
        
</asp:Repeater>
              
               
               </div>

 <script type="text/javascript" >

        function singleselection(rbid) {
            var rbutton = document.getElementById(rbid);
            var rbuttonlist = document.getElementsByTagName("input")
            for (i = 0; i < rbuttonlist.length; i++) {
                if (rbuttonlist[i].type == "radio" && rbuttonlist[i].id !== rbutton.id) {
                    rbuttonlist[i].checked = false;
                }
                
            }
        }

    </script>

If the above code runs none of the radio button selected , if user clicks then its selecting , but i want by default select 1st option and then if user select any option then select only that option, this page is like selecting the address. Please someone help on this.