You can change your get_posts $args
Example:
$args = array(
'orderby' => 'rand',
'category_name' => 'your_category',
'showposts' => 1
);
You can change your get_posts $args
Example:
$args = array(
'orderby' => 'rand',
'category_name' => 'your_category',
'showposts' => 1
);