Between the word "beliefs" (which rules out most demographic groups), the word "openly" (which rules out anything you can't easily hide), and the existence of a plausible "anti-X" group (which rules out most multipolar situations), there's not too many possibilities left. The correct answer is the biggest, and most of the other plausible options are subsets of it.

I suppose it could also have been its converse, but you don't hear too much about discrimination cases going that way.