<select name="region">
	<option value="1">NCR</option>
	<option value="2">Region 1</option>
	<option value="3">Region 2</option>
	<option value="4">Region 3</option>
</select>

<select name="city">
	<option value="1" class="ncr">Makati</option>
	<option value="2" class="ncr">Manila</option>
	<option value="3" class="ncr">Quezon</option>
	<option value="4" class="ncr">Pasay</option>
	<option value="5" class="r1">Ilocos</option>
	<option value="6" class="r1">Isabela</option>
	<option value="7" class="r1">Cagayan</option>
	<option value="8" class="r1">Tarlac</option>
</select>


<script>

	var ncr = $('.ncr');
	var r1 = $('.r1');

	ncr.hide();
	r1.hide();

	$('select[name=region]').change(function(){
		var regionVal = $(this).val();

		switch(regionVal){

			case 1:
				ncr.show();
				r1.hide();

			case 2:
				ncr.hide();
				r1.show();

		}




	});



</script>