What is the relationship between ADNOC and Abu Dhabi in the context of the input sentence. Choose an answer from: 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.

We are currently providing facility management services in 3 countries with blue chip clients, including the Abu Dhabi National Oil Company, ADNOC, for its entire portfolio of ADNOC facilities.

Answer: headquarters_location