What is the relationship between Reliance Communications and MUMBAI 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.

MUMBAI (Reuters) - Mobile telecoms operator Reliance Communications Ltd will partner conglomerate Reliance Industries Ltd's telecoms unit to trade and share mobile airwaves and offer high-speed 4G services.

Answer: headquarters_location