"Ellas se cepillan el cabello en el baño."
Translation:They brush their hair in the bathroom.
They brush their hair in the bath should be accepted too. baño means bath its use as bathroom is an abreviation of cuatro de baño, room of the bath
Lav was accepted, but not bath?
In the US the only time I ever hear the word "lavatory" is on airplanes. I guess they want to make sure we understand there is no actual bath in those tiny little outhouses they have on planes.