How do i enable RadioButtonList sub control?

Hi,

How do i enable RadioButtonList sub control?

ex
<asp:RadioButtonList ID="ID1" runat="server" RepeatDirection="Horizontal"
ClientIDMode="Static" >
<asp:ListItem Text="A" Value="a"></asp:ListItem>
<asp:ListItem Text="B" Value="b"></asp:ListItem>
</asp:RadioButtonList>

Here i need to enabled ListItem, Whose Text is A, is to be enabled