So draw is most one can get. Underpromoting to knight (with check, thus avoiding the check by the bishop) is the only way to promote and keep the piece another move.
I guess in this situation the knight against two bishops keeps the draw.
So the correct move is to move the Pawn up and promote to knight?
Thanks!
Yes, though - I think I can say without exaggeration - no human on earth can tell you exactly which positions the knight can hold out against the bishops for the required 50 moves.
So it's a strange problem: a perceptive beginner can find the right move through a process of elimination, but even a super-GM can't be certain it's good enough, or defend it accurately against a computer. I don't see anything about that that makes it a particularly good test of an LLM.