How to Display Custom Options in Magento

$productSku = "ABCDE";
$product = Mage::getModel('catalog/product');
$productId = $product->getIdBySku( $productSku );
$product->load($productId);

/**
 * In Magento Models or database schema level, the product's 

Custom Options are
 * executed & maintained as only "options". So, when checking 

whether any product has
 * Custom Options or not, we should check by using this method 

"hasOptions()" only.
 */
if($product->hasOptions()) {
    echo '<pre>';

    foreach ($product->getOptions() as $o) {
        $optionType = $o->getType();
        echo 'Type = '.$optionType;

        if ($optionType == 'drop_down') {
            $values = $o->getValues();

            foreach ($values as $k => $v) {
                print_r($v);
            }
        }
        else {
            print_r($o);
        }
    }

    echo '</pre>';
}