How to sort WP Query to display each product category? [Woocommerce]

I have 12 “main” categories that my products fall under, I don’t want to display each product, only the parent category they are under. Is there an argument I can place in this query?

Here is what I have so far:

<?php
$product_loop = new WP_Query( array(
    'post_type' => 'product',
    'posts_per_page' => 12
  )
);
?>

<section id="products-home">
  <?php if($product_loop) : ?>
    <div class="container">
      <div class="row">
        <?php while ( $product_loop->have_posts() ) : $product_loop->the_post(); ?>
        <div class="col-md-3">
          <?php the_post_thumbnail( 'full', array( 'class' => 'img-responsive' ) ); ?>
          <h3><?php echo the_title(); ?></h3>
        </div>
        <?php endwhile; ?>
      </div>
    </div>
  <?php endif; ?>
</section>