on the basis of your only jQuery tag :)
HTML
<select id="my-select">
<option value="1">This is text 1</option>
<option value="2">This is text 2</option>
<option value="3">This is text 3</option>
</select>
For text --
$(document).ready(function() {
$("#my-select").change(function() {
alert($('#my-select option:selected').html());
});
});
For value --
$(document).ready(function() {
$("#my-select").change(function() {
alert($(this).val());
});
});