[jquery] Using JQuery - preventing form from submitting

How do I prevent a form from submitting using jquery?

I tried everything - see 3 different options I tried below, but it all won't work:

    $(document).ready(function() { 

            //option A
            $("#form").submit(function(e){
                e.preventDefault();
            });

            //option B
            $("#form").submit(function(e){
                stopEvent(e);
            });

            //option C
            $("#form").submit(function(){
                return false;
            });
    });

What could be wrong?

Update - here is my html:

    <form id="form" class="form" action="page2.php" method="post"> 
       <!-- tags in the form -->
       <p class="class2">
           <input type="submit" value="Okay!" /> 
       </p>
    </form>

Is there anything wrong here?