Populate Select List with Custom Post Type Name

Pretty common request, have reviewed a lot of documentation but still can't nail it down. My custom post type is "staffmembers" -- I think this is in the ballpark, but was wondering what I have wrong. Thanks in advance.

$options = array();
$post_types = get_post_types( '', 'staffmembers', 'objects' );

foreach ( $post_types as $post_type ) {
    $options[$post_type->slug] = $post_type->name;
}

add_filter( 'rwmb_meta_boxes', 'your_prefix_register_meta_boxes' );
function your_prefix_register_meta_boxes( $meta_boxes ) {
    $meta_boxes[] = array (
      'id' => 'author',
      'title' => 'Author',
      'pages' =>   array (
         'post',
      ),
      'context' => 'normal',
      'priority' => 'high',
      'autosave' => false,
      'fields' =>   array (
         
        array (
          'id' => 'select_2',
          'name' => 'Select Field',
          'type' => 'select',
          'placeholder' => 'Select an Item',
          'options' =>       $options,
        ),
      ),
      '' => '',
    );

    return $meta_boxes;
}