I think "That so irritated him that he left the room" would also be a correct response.
That's what I put but I got it wrong. I had to put "nervy" in order to finish the lesson. Of course I reported this because nervy doesn't mean irritated in English. It means bold or audacious.
"That irritated him so much he left the room" rejected.
That irritated him so much that he left the room?
I agree with PhilSchnyder
Perhaps not enough different translations have been proposed yet.