Maybe I've been too close to the front at recitals all these years, but I suggest (c) no
microphone, especially if there are several dancers. Metal on wood carries well. (I always thought that the footwork was the most important part and the tapping sound an ornamentation.)
But if you still need to have a
microphone on the dancer(s), remember that the dancer(s) will probably need to hear the music she (they? he?) is dancing to; that she'll (they'll) be moving all over the
stage – up, down, left, right; and that with some heel-toe combinations, the heel will be a pound not a tap.
Joe