Utilize the input text as a context reference, choose the right relationship between Tim Cook and Chief Executive Officer from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Sept 18 Apple Inc is stepping up aid to the thousands of migrants that are streaming into Europe from war-torn countries, Chief Executive Officer Tim Cook told employees in an internal message on Friday.

Answer: position_held