I think my answer was more intuitive than an act of figuring out the actual logic.
In the stimulus he explains what perception can't be, and his reasoing is that there imperceivable things that we have beliefs.
My logic was, that's great, just because we have beliefs about imperceptable things, that says nothing about things we DO perceive.
In other words, it tries to define something by what it's not. "A" does the exact same thing. "Art is not..., because we know such and such about what art isn't"
Right, so I know my explanation was worthless. I guess, in truth, A just seemed to mimic the stimulus exactly. Take it for what you will.