You're given a sentence and your task is to classify whether the sentence is acceptable or not. Any sentence which is grammatically correct, has a naturalistic text, is written by a native speaker and which minimizes superfluous content is acceptable, otherwise unacceptable. If the sentence is acceptable then write "acceptable", otherwise "unacceptable".

Jennifer craned her arm.
unacceptable

Bob proved that this set is recursive.
acceptable

They want to hire someone who speaks a Balkan language, but I don't know which language.

unacceptable