(Reuters) - Online gambling firm 888 Holdings (888.L) stepped up a billion pound battle for Bwin.party Digital Entertainment (BPTY.L) on Tuesday, submitting a revised takeover proposal as it looks to see off rival interest from GVC Holdings (GVC.L).
In the context of the input sentence, determine the relationship between '888 Holdings' and 'gambling'.
Options: creator, industry, founded by, chief executive officer