title: Only one checkbox to be selected
body: <p>I would like to only have single checkbox selected at a time. My program reads from a textfile and creates checkboxes according to how many "answers" there are in the textfile. </p>
  
  <p>Does anyone know what is wrong with the code?</p>
  
  <pre><code>public partial class Form1 : Form
  
      {
          string temp = "questions.txt";
  
          public Form1()
          {
              InitializeComponent();
          }
  
          private void Form1_Load(object sender, EventArgs e)
          {
              StreamReader sr = new StreamReader(temp);
              string line = "";
              List&lt;string&gt; enLista = new List&lt;string&gt;();
              while ((line = sr.ReadLine()) != null)
              {
                  string[] myarray = line.Split('\r');
                  enLista.Add(myarray[0]);
  
  
              }
              sr.Close();
  
  
              for (int i = 0; i &lt; enLista.Count; i++)
              {
                  if (enLista[i].Contains("?"))
                  {
                      Label lbl = new Label();
                      lbl.Text = enLista[i].ToString();
                      lbl.AutoSize = true;
                      flowLayoutPanel1.Controls.Add(lbl);
                  }
                  else if (enLista[i] == "")
                  {
  
                  }
                  else
                  {
                      CheckBox chk = new CheckBox();
                      chk.Text = enLista[i].ToString();
                      flowLayoutPanel1.Controls.Add(chk);
                      chk.Click += chk_Click;
                  }
              }
  
          }
          private void chk_Click(object sender, EventArgs e)
          {
              CheckBox activeCheckBox = sender as CheckBox;
              foreach (Control c in Controls)
              {
                  CheckBox checkBox = c as CheckBox;
                  if (checkBox != null)
                  {
                      if (!checkBox.Equals(activeCheckBox))
                      { checkBox.Checked = !activeCheckBox.Checked; }
                      else
                      { checkBox.Checked = true; }
                  }
              }
          }
      }
  </code></pre>