What is the relationship between Ausgrid and Sydney 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.

For households in the area served by Ausgrid - the inner city, eastern and the northern suburbs, extending to Newcastle - the difference between the highest and lowest offers is $400, with the difference between the highest and lowest a more modest $285 in western and southern Sydney and also Wollongong, which is the area served by Endeavour Energy.

Answer: headquarters_location