All the options presented to me through the UI do not seem to address the situation correctly. Here is a screenshot of the options available to me.
And here are the Share Feedback options.
The only one that seems applicable is to just edit the question to be the correct one. But are those really the only solutions?
My first instinct is to tell the answerer that their answer is wrong. But none of the feedback options seem to encourage it. In fact, they seem to shy away from the "obvious" reaction. Perhaps that is intentional, based on this website's reputation.
But I guess, as a side question, is it implying that the solution here is to just fix bad answers? I am not opposed to doing that, but I really want to make sure that that is the intended strategy before applying (what I believe to be) a very blunt hammer to a situation that is delicate (a new user giving their first answer ever on this website). It feels like a very blunt "how-do-you-do" for someone trying to learn, not to mention we are fixing the problem for them, rather than teaching them to do it themselves.
And I would absolutely like to avoid flagging. The answer isn't garbage, but it makes a bad assumption at its core. Here is the answer on the review queue.
And in case the answer gets removed from the queue, here is the direct link to the answer.
Finally, I should add that the edit that I would have made anyways would effectively be a direct copy of a fellow answer on the question.
EDIT - Upon a deeper inspection, the answer is just fundamentally wrong, not just a bad assumption.