Question:You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5.
You create two user controls named UserCtrlA.ascx and UserCtrlB.ascx. The user controls postback to the server.
You create a new Web page that has the following ASPX code:
<asp:CheckBox ID="Chk" runat="server"
oncheckedchanged="Chk_CheckedChanged"
AutoPostBack="true" />
<asp:PlaceHolder ID="PlHolder" runat="server"></asp:PlaceHolder>
To dynamically create the user controls, you write the following code segment for the Web page:
public void LoadControls()
{
 if (ViewState["CtrlA"] != null)
 {
  Control c;
  if ((bool)ViewState["CtrlA"] == true)
  {
   c = LoadControl("UserCtrlA.ascx");
  } else {
   c = LoadControl("UserCtrlB.ascx");
  }
  c.ID = "Ctrl";
  PlHolder.Controls.Add(c);
 }
}
protected void Chk_CheckedChanged(object sender, EventArgs e)
{
 ViewState["CtrlA"] = Chk.Checked;
 PlHolder.Controls.Clear();
 LoadControls();
}
You need to ensure that the user control that is displayed meets the following requirements:
It is recreated during postback
It retains its state.
Which method should you add to the Web page? 

A protected override object SaveViewState() {
 LoadControls();
 return base.SaveViewState();

B protected override void Render(HtmlTextWriter writer) {
 LoadControls();
 base.Render(writer);

C protected override void OnLoadComplete(EventArgs e) {
 base.OnLoadComplete(e);
 LoadControls();

D protected override void LoadViewState(object savedState) {
 base.LoadViewState(savedState);
 LoadControls();

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