This mainly echos what Jim Belk said. On a comment flag we can do exactly three things:
- delete the comment
- edit the comment
- dismiss the flag, i.e., do nothing
In the present situation an edit cannot really help, so we could only delete, but this is rather not a good idea as relevant information could be lost. So, we are stuck with doing nothing.
What one could do if one feels somebody made a comment that would better be an answer, is to comment(reply) that they could/should expand the comment to an answer. (There is also nothing wrong with somebody else giving what is in a comment as an answer.)
However, I would also say there likely should be some room for half-way or tentative answers in comments. For example, one of the comments ended with a question mark. Perhaps OP was really not sure this would actually be an answer and wanted to "test" it as a comment first.
And additional point to keep in mind, and relevant in the current situations, is that the question is "protected" so that for some users commenting is possible but answering is not.
(While the point limit for commenting is higher than that for answering protected questions, this can still happen since for commenting the association bonus counts while for answering protected questions it does not count.)
Generally, regarding which flag to use: when in some doubt I would say best use "other" and explain what it is about. It can be difficult to understand what precisely is meant.
(In the end, I also deleted one comment, since it duplicated an actual answer, actually two answers.)