Analyze the relationship between 'Betfair' and 'online gambling' within the context of the input sentence.
Options: industry, creator, brand, member of

On the upside, shares in mid-cap Betfair soared 17 percent after the online gambling company and Irish rival Paddy Power said they had reached an agreement in principle on a possible merger, marking the latest in a string of possible tie-ups across the sector.
industry