I want to know the answer to the following question:
When was the Behistun inscription written?
All the background I'm provided with is that "Genuine Old Persian is best attested in one of the three languages of the Behistun inscription, composed circa 520 BC, and which is the last inscription (and only inscription of significant length) in which Old Persian is still grammatically correct.". Is that enough to answer the question?
Answer: yes