Utilize the input text as a context reference, choose the right relationship between 'Vittorio Colao' and 'Vodafone' from the options.
Options: employer, platform, developer, operator

LONDON, July 21 (Reuters) - Vodafone said the bosses of its four biggest European markets would report directly to chief Vittorio Colao to speed up decision making in fast-changing markets, after it decided to scrap its European regional management structure.
employer