Select only one CheckBox from group of CheckBoxes in GroupBox ( Mutually Exclusive ) in Windows Forms Application

Assign the same following CheckChanged event to all CheckBoxes

  private void CheckBox_Changed(object sender, EventArgs e)
        {
            if ((sender as CheckBox).Checked)
            {
                foreach (CheckBox c in groupBox1.Controls.OfType<CheckBox>())
                {
                    if (c != (sender as CheckBox))
                    {
                        c.Checked = false;
                    }
                }
            }
        }  

And you must have the following namespace inherited

using System.Linq;