<select id="sel1">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<select id="sel2">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<select id="sel3">
<option>A</option>
<option>B</option>
<option>C</option>
</select>
<script type="text/javascript">
$(document).ready(function () {
$("select").change(function () {
var id = $(this).attr("id");
alert (id);
});
});
</script>