Take context from the input text and decide on the accurate relationship between 'National Geographic Society' and 'National Geographic' from the options provided.
Options: employer, headquarters location, owner of, subsidiary

The National Geographic Society and 21st Century Fox announced today that they have reached an agreement to expand their highly successful 18-year partnership through which they have owned and operated the properties in National Geographic Channels, a joint venture of domestic and international cable television channels which together reach more than 500 million households globally.
owner of