You would need to use a data attribute to store the text, unless you know of a plugin which has some kind of AI and knows it's alphabet and can return a string.

<select id="321" name="123">
    <option value="a" data-message="A is the first letter of the alphabet!">a</option>
    <option value="b" data-message="B is the second letter of the alphabet!">b</option>
    <option value="c" data-message="C is the third letter of the alphabet!">c</option>
    <option value="d" data-message="D is the fourth letter of the alphabet!">d</option>
</select>
<div id="help"></div>

$('#321').change(function() {
    $('#help').text($('option:selected', this).data('message'));
});

here is another solution for this issue :

<select id="321" name="123">
    <option id='a' value="a">a</option>
    <option id='b' value="b">b</option>
    <option id='c' value="c">c</option>
    <option id='d' value="d">d</option>
</select>
<div id="help"></div>
<script>
    $(document).ready(function (){
        var alghabet = new Array('first','second','third','fourth');
        $("option").hover(
        function() {
            var i = $(this).index();
            var value = $(this).attr("value").toUpperCase();
            $("#help").html(value + " is the " + alghabet[i] + " letter of the alphabet!");
        }
    );
    });
</script>