Manually Display Images

I am manually outputting user specific recent comments on author pages and I wasn’t sure how to output the image in my code. I currently have the following in my author template file, which lists the post title (with a link to the comment), the comment itself, and the comment post date. How can I output a thumbnail of the image with the zoom feature?

$author = get_query_var( ‘author’ );
$author = get_user_by( ‘id’, $author );

$args = array(
‘user_id’ => $author->ID,
‘number’ => 10, // how many comments to retrieve
‘status’ => ‘approve’
);

$comments = get_comments( $args );

if ( $comments )
{
$output.= “

\n”;
foreach ( $comments as $c )
{
$output.= ‘
• ‘;
  $output.= ‘<h4>comment_ID ).'”>’;
  $output.= get_the_title($c->comment_post_ID).’</h4>’;
  $output.= ‘<p>’.$c->comment_content.'</p>’;
  $output.= ‘<span class=”pro-comment-date”>Posted on: ‘. mysql2date(‘m/d/Y’, $c->comment_date, $translate).'</span>’;
  $output.= “

\n”;
}
$output.= ‘

‘;

echo $output;
} else { echo “No reviews made recently”;}