How to display only the first category that a Post belongs to in Genesis. http://sridharkatakam.com/display-first-category-post-belongs-genesis/

functions.php

<?php
//* Do NOT include the opening php tag

add_shortcode( 'post_category', 'sk_show_the_first_category_name_only' );
/**
 * Custom shortcode that returns the first hyperlinked category that entry belongs to
 *
 * @author Sridhar Katakam
 * @link   http://codex.wordpress.org/Function_Reference/get_the_category#Show_the_First_Category_Name_Only
 */
function sk_show_the_first_category_name_only( $atts ) {
	$categories = get_the_category( $post->ID );

	if( $categories[0] ) {
		return 'Filed Under: <a href="' . get_category_link( $categories[0]->term_id ) . '">' . $categories[0]->cat_name . '</a>';
	}

}

add_filter( 'genesis_post_meta', 'sk_post_meta_filter' );
/**
 * Customize entry meta in the entry footer
 * We are replacing [post_categories] with a custom shortcode, [post_category]
 *
 * @author Sridhar Katakam
 * @link   http://sridharkatakam.com/display-first-category-post-belongs-genesis/
 */
function sk_post_meta_filter( $post_meta ) {
	$post_meta = '[post_category] [post_tags]';
	return $post_meta;
}