How do I disagree with a flag?

Question

I was inspecting a flag of this answer because it was low quality. It was indeed low quailty, but only because it didn't have references or numbers (factual information).

I posted a comment asking the user to provide the factual information to upgrade it from poor to acceptable.

1. What should I have done with this flag since there was a chance to salvage the answer with factual information
2. How do I disagree with a flag? I didn't see any options to do so

Here is what I see

When I click the flag or disagree button, I see this

Answer 1

1. I also don't agree so much with the heavy use of flags instead of downvotes for what are actually just bad answers, but I also see that the use of the "low quality"-flag is not that easy to decide. I for myself think that the "low quality"-flag is usually unneccessary since answer quality is easily expressed through simple voting. But I also will not cast an "invalid flags"-flag for now, since I cannot deny the fact that this answer certainly is of "very low quality", at least not until it garneres "not an answer"-flags, which would be entirely wrong, given that it definitely is a valid answer, albeit a bad one. But if you don't agree with the flag, then feel free to disagree with it.

2. As to the technical part of the question, in the flag review section there is a button under each individual flag reading flag or disagree.... Clicking it will open a window with multiple options, one of them being it has invalid flags. Select this one and click Flag Answer.