I am creating a Dropdown selection box with a list of custom post types with them prefixed by their category name. Each post will only have one category name. This is what I have at the moment. How would I sort them by the Category Name?

echo '<option value="-1">--Select a Product--</option>';
while ( $query->have_posts() ) : $query->the_post();
	$id = get_the_ID();
	echo '<option value="' .$id. '"' .selected( $product, $id ). '>';
	$category = get_the_terms( $id->ID, 'product_cat' );
	foreach ( $category as $cat){
	   echo $cat->name . ' - ';
	}
	the_title();
	echo '</option>';
endwhile;

[Moderator note: code fixed. Please wrap code in the backtick character or use the code button.]

Any insights into a solution are greatly appreciated.

– Michael