I’m assuming by boy you mean he has a male genitals. Schools and teachers can’t discuss this stuff. There’s far too many legal and social issues now. It’s easier for the coach and principle to refer you to the school board. All they care about is keeping their job and their pension. The last thing they want is to be fired for having a discussion. I would bet the coach and principle agree it’s ridiculous behind closed doors. But if they told you that you’d tell someone and they’d be fired and lose their salary and pension.
My opinion is just ignore it. Sure, your daughter won’t win any races and that sucks for her self esteem, but maybe it’ll help her train harder. Eventually the boy will reach a level where he is banned from competing. It’s into a matter of time until someone takes advantage of the situation. Right now it’s only boys who genuinely identify as girls. So that’s fine if it’s genuine. But sooner rather than later it’ll be boys who identify as boys but say they are girls just to win races. If you’re a 10:00 minute 3200 runner in high school, you’ll never win anything. But as a girl? You can chase the National record. Eventually that’ll happen. Just be patient. You say it won’t, but it will.
Be funny seeing a mountain man beard and hairy chest boy with no shirt on taking girl’s national record photos. Good laughs are coming. Or maybe someone will make it really ridiculous and an 8:59 3200 and 4:08 1600 boy says they are a girl. There’s gotta be a high schooler reading this who wants to take one for the team? All it takes is one like that and you’ll change the world. You’ll put a stop to all this nonsense.