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.
In the context of the input sentence, determine the relationship between 'British Gas' and 'Centrica'.
Options: business division, owned by, member of, publisher