Utilize the input text as a context reference, choose the right relationship between 'Heathrow hub' and 'London' from the options.
Options: publisher, distributed by, founded by, headquarters location

A clue to BA's lingering love affair with the 747 lies in the model's ability to eke out capacity from scarce operating slots at its London Heathrow hub at a time when lower fuel prices make retaining older planes an option.
headquarters location