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".

Q: I am frightened of tigers.

A: acceptable
****
Q: I bought the parrot in the store.

A: acceptable
****
Q: I gave a gun to my brother which I had cleaned.

A:
acceptable
****