/* Only Show Primary Category in Single Post */
function only_show_primary_category( $thelist ) {
	if ( is_single() && is_singular() ) {
		$cat_id = jnews_get_primary_category( get_the_ID() );
		$cat = get_term( $cat_id, 'category' );
		$primary_cat = '' . $cat->name . '';
		return $primary_cat;
	}

	return $thelist;
}
add_filter( 'the_category', 'only_show_primary_category', 999 );