woocommerce/templates/single-product/add-to-cart/variable.php

<?php
/**
 * Variable Product Add to Cart
 */
 
global $woocommerce, $product, $available_variations, $attributes, $selected_attributes;
?>
<script type="text/javascript">
    var product_variations = <?php echo json_encode($available_variations) ?>;
</script>

<?php do_action('woocommerce_before_add_to_cart_form'); ?>

<form action="<?php echo esc_url( $product->add_to_cart_url() ); ?>" class="variations_form cart" method="post" enctype='multipart/form-data'>
	<table class="variations" cellspacing="0">
		<tbody>
		<?php foreach ($attributes as $name => $options) : ?>
			<tr>
				<td><label for="<?php echo sanitize_title($name); ?>"><?php echo $woocommerce->attribute_label($name); ?></label></td>
				<td><select id="<?php echo esc_attr( sanitize_title($name) ); ?>" name="attribute_<?php echo sanitize_title($name); ?>">
					<option value=""><?php echo __('Choose an option', 'woothemes') ?>&hellip;</option>
					<?php if(is_array($options)) : ?>
						<?php
							$selected_value = (isset($selected_attributes[sanitize_title($name)])) ? $selected_attributes[sanitize_title($name)] : '';
							// Get terms if this is a taxonomy - ordered
							if (taxonomy_exists(sanitize_title($name))) :
								$args = array('menu_order' => 'ASC');
								$terms = get_terms( sanitize_title($name), $args );

								foreach ($terms as $term) :
									if (!in_array($term->slug, $options)) continue;
									echo '<option value="'.$term->slug.'" '.selected($selected_value, $term->slug).'>'.$term->name.'</option>';
								endforeach;
							else :
								foreach ($options as $option) :
									echo '<option value="'.$option.'" '.selected($selected_value, $option).'>'.$option.'</option>';
								endforeach;
							endif;
						?>
					<?php endif;?>
				</td>
			</tr>
        <?php endforeach;?>
		</tbody>
	</table>

	<?php do_action('woocommerce_before_add_to_cart_button'); ?>

	<div class="single_variation_wrap" style="display:none;">
		<div class="single_variation"></div>
		<div class="variations_button">
			<input type="hidden" name="variation_id" value="" />
			<?php woocommerce_quantity_input(); ?>
			<button type="submit" class="button alt"><?php _e('Add to cart', 'woothemes'); ?></button>
		</div>
	</div>
	<div><input type="hidden" name="product_id" value="<?php echo esc_attr( $post->ID ); ?>" /></div>

	<?php do_action('woocommerce_after_add_to_cart_button'); ?>

</form>

<?php do_action('woocommerce_after_add_to_cart_form'); ?>