Utilize the input text as a context reference, choose the right relationship between 'Vittorio Colao' and 'Vodafone' from the options.
Options: chief executive officer, original broadcaster, owned by, employer

Vodafone chief executive Vittorio Colao has promoted the leaders of the company’s biggest European markets to his top table, even as the networks they run are at the centre of talks about a potential combination with Liberty Global (NasdaqGS: LBTYA - news ) .
employer