What is the relationship between 'Vittorio Colao' and 'Vodafone' in the context of the input sentence.
Options: chief executive officer, employer, owned by, original broadcaster

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