Given this checkbox html element:
<h4>This is a question?</h4>
<input type="radio" value="1" name="q">answer 1</input>
<input type="radio" value="2" name="q">answer 2</input>
<input type="radio" value="3" name="q">answer 3</input>
How can I lock the state of a checkbox after it has been selected? That is, how can I avoid the user to change his answer?