如何使用C#从.txt文件中获取随机单词?

private async void Button_Click(object sender, RoutedEventArgs e)
    {
        int word = 1;
        string FileName;
        openFileDialog1.Filter = "txt files (*.txt)|*.txt";
        openFileDialog1.FilterIndex = 2;
        openFileDialog1.InitialDirectory = @"C:\";
        openFileDialog1.RestoreDirectory = true;
        openFileDialog1.ShowDialog();
        FileName = openFileDialog1.FileName;
        FileStream stream = File.Open(FileName, FileMode.Open);
        await Task.Run(() =>
        {
            using (StreamReader reader = new StreamReader(FileName))
            {
                string content = reader.ReadToEnd();
            }
        });
    }

如您所见,我决定创建一个“内容”字符串,其中将包含.txt文件中的所有文本。现在如何从这个不是数组的字符串中选择一个随机单词?