<span>By far, the most obvious advantage of using a wireless microphone is the fact that the user can move unimpeded when performing. The greatest advantage to using a wireless, clip-on microphone is also that, the speaker or the singer can wander freely around the stage without losing the quality of the sound. Hope this answer helps.</span>
Some generally refers to a bigger amount that a little, but is not a lot, that is probably a confusing way to explain so i am sorry
Im my opinoin id say both a and d but id go wit d to be safe