It is based on my knowledge of the popular television show ‘who wants to be a millionaire’ and my limited experience in coding some multiple choice online games.
millionaire only ever has one answer per question that is correct, that’s the format of the show, that doesn’t change ever, there doesn’t exist an option of two possible answers. So the ‘right answer’ has been assigned to a, b, c or d. It doesn’t really matter if the ‘right answer’ is actually factually true, it only matters that it has been given the ‘right answer’ condition, so even though there are two 25% options in the above example - only one of them can be the ‘right answer’ because of how the game is set up.
So in this scenario you could choose one of the 25% answers and still get the question ‘wrong’, which would be pretty annoying if you lost 30k or something, but that’s really something you’d have to take up with the production company behind ‘who wants to be a millionaire’