The competition watchdog said in March that it had granted permission for British Gas Trading (BGT) - a subsidiary of Centrica (LSE: CNA.L - news ) , the UK's biggest energy supplier - and Northern Powergrid to appeal against Ofgem's price control decision.
Refer to the input text as context and select the correct relationship between 'Centrica' and 'British Gas' from the available options.
Options: owner of, brand, headquarters location, distribution format