I hardly ever hear the word bafu used in Tanzania. I usually hear choo(believe it means toilet) or msalani(used for nicer bathroom not for outside toilet)
Bafu is used for the shower area only. Choo only means where you relieve yourself. Msalani could maybe be translated to restroom, or washing area, this is like you said mostly on signs in restaurants or hotels.
Why in the prompt is 'choo' but the corect answer is different?
probably something that still needs to be reported