While flagging questions, there is a detailed system explaining exactly what each option means, but there is no such thing while flagging comments. The help section also does not give any specific examples. Can a system for flagging comments be created just like the one for flagging questions?
Because comments are designed to be ephemeral and second-class objects, we don't maintain nearly as much formality in dealing with them. Take you best guess and go with it.
It bears repeating: any comment can be deleted at any time for any reason or none. Nothing important should be left in the comments: important ideas should make their way into first class posts lest they be lost.