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<?php

add_filter('ninja_forms_render_options','fc_pre_population_callback', 10, 2);
function fc_pre_population_callback($options, $settings) {
  
  	if (is_singular('contact-forms') and $settings['key'] == 'business_location') {

		$locations = get_field('business_locations', get_the_ID());
		$options = array();

		foreach($locations as $location) {
			$options[] = array(
				'label' => $location['location'],
				'value' => $location['emails']
			);
		}

  	}
  
   	return $options;
}