For this kind of question, sometimes I find it helps to imagine you're having a conversation. So let's say you're Jane and you state her opinion. And that Mark is your friend, and that mark replies to you with his opinion. Is Mark agreeing with you? Disagreeing? Getting to the same conclusion but in a different way?
Jane is saying Harper's ideas have no value for design (i.e., they don't result in superior sound), because there's no accepted basis for evaluating the merits of a guitar's sound.
Mark is saying Harper's ideas don't result in superior design, because if they did, they would have been universally accepted.
Jane and Mark are agreeing that Harper's guitars are not of value/don't improve the sound, but they get there in different ways. Jane says it's because there's no basis for evaluating this, and Mark says it's because if they were better they would be universal.
So, option A? No because Mark is not focusing on a weakness in Jane's argument, just saying something different. B) No because they reach the same conclusion, its the premise that differs. C) No because they are using different techniques to argue for the same conclusion (C is the reverse of what we would want). D) This is tricky, but remember an argument means premises + conclusion, not just conclusion. Although they reach the same conclusion, they do so in very different ways, and Mark has his own argument, not just restating Jane. E) This is right because Mark's whole idea, that if they were actually better they would be universal by now, directly contradicts Jane's idea that there is no universal basis for evaluating a guitar's sound.
