When I choose to put a bounty on a question, it asks me why. I get the choice of:
Authoritative reference needed
Looking for an answer drawing from credible and/or official sources.
Canonical answer required
The question is widely applicable to a large audience. A detailed canonical answer is required to address all the concerns.
Current answers are outdated
The current answer(s) are out-of-date and require revision given recent changes.
This question has not received enough attention.
The current answers do not contain enough detail.
Reward existing answer
One or more of the answers is exemplary and worthy of an additional bounty.
What if the current answers are just wrong? They're answering the wrong question, or just factually incorrect? The closest I can see is "improve details", but shouldn't there be a "need a correct answer" option?
If the answers are wrong, just use a "Draw Attention" reason. In your bounty message you can then state that the current answers are inaccurate (perhaps briefly detailing how so) and that you are looking for a correct answer.