how To subsribe to event in user control in wpf

<usercontrol x:class="WpfApplication1.UserControl1" xmlns:x="#unknown">
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="103" d:DesignWidth="134"
             Background="AliceBlue"
             Margin="10">
    <grid height="81" width="111" background="AntiqueWhite">
        <radiobutton content="Option A" height="16" horizontalalignment="Left" margin="12,9,0,0" name="radioButtonA" verticalalignment="Top" checked="radioButton_CheckedChanged" />
        <radiobutton content="Option B" height="16" horizontalalignment="Left" margin="12,31,0,0" name="radioButtonB" verticalalignment="Top" checked="radioButton_CheckedChanged" />
        <radiobutton content="Option C" height="16" horizontalalignment="Left" margin="12,53,0,0" name="radioButtonC" verticalalignment="Top" checked="radioButton_CheckedChanged" />
    </grid>
</usercontrol>

public partial class UserControl1 : UserControl
    {
        public delegate void OptionChangedEventHandler(UserControl1 sender, RadioButton radioButton, bool? checkedState);
        public event OptionChangedEventHandler OptionChanged;

        public UserControl1()
        {
            InitializeComponent();
        }

        public string DisplayName { get; set; }

        private void radioButton_CheckedChanged(object sender, RoutedEventArgs e)
        {
            if (this.OptionChanged != null)
                this.OptionChanged(this, sender as RadioButton, (sender as RadioButton).IsChecked);
        }
    }

<window x:class="WpfApplication1.MainWindow" xmlns:x="#unknown">
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <grid>
        <stackpanel>
            <button content="Add User Control" click="Button_Click" height="30" />
            <wrappanel name="wrapPanel" orientation="Vertical" />
        </stackpanel>
    </grid>
</window>

public partial class MainWindow : Window
    {
        private static int i = 0;
        
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            UserControl1 uc = new UserControl1() { DisplayName = "User Control " + (i++).ToString() };
            uc.OptionChanged+=new UserControl1.OptionChangedEventHandler(uc_OptionChanged);
            wrapPanel.Children.Add(uc);
        }

        void uc_OptionChanged(UserControl1 sender, RadioButton radioButton, bool? checkedState)
        {
            MessageBox.Show(String.Format("'{0}' = '{1}' for User Control '{2}'", radioButton.Content, checkedState, sender.DisplayName));
        }
    }