Jquery - Set RadioButtonList First ListItem As Selected

I am using jquery and c# to dynamically set a radiobuttonlist listitem to selected. I want to create a reset-type button to reset the radiobuttonlist selected item back to the first item in the list. jQuery/jsTree function currently reseting textbox and hidden field:

$('#ContentPlaceHolder1_hfNodeID').val('');
$('.txtPage').val('');
$('.rblContentTypesGetAll').val();
$('.contentPageForm').show(),
.rblContentTypesGetAll is the radiobuttonlist i want to reset (or select the top most listitem).
HTML of the form:
<asp:Panel ID="PagesForm" CssClass="contentPageForm" runat="server">
<asp:HiddenField ID="hfNodeID" runat="server" Value="" />
<table>
<tr>
<td>Page</td>
<td><asp:TextBox ID="txtPage" CssClass="txtPage" runat="server" /><span class="validate">*</span><br />
<asp:RequiredFieldValidator ID="rfvPage" runat="server" CssClass="validate" ControlToValidate="txtPage" Display="Dynamic" ErrorMessage="Page Name Required" ValidationGroup="page" /></td>
</tr>
<tr>
<td>Content Type</td>
<td>
<asp:RadioButtonList id="rblContentTypesGetAll" CssClass="rblContentTypesGetAll" OnLoad="rblContentTypesGetAll_Load" runat="server" >
</asp:RadioButtonList>
</td>
</tr>
<tr>
<td> <asp:Button ID="Submit" runat="server" OnClick="PageSubmit_Click" Text="Save" ValidationGroup="page" />
<asp:Button ID="Cancel" runat="server" OnClick="Cancel_Click" Text="Cancel" />
</td>
</tr>
</table>
</asp:Panel>