Utilize the input text as a context reference, choose the right relationship between Ausgrid and Sydney 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.

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