Could you please explain this question and answer?

I would find a breakdown helpful too. Thank you!

Hi, we are told that a good design has gone through many drafts and improved over time. The process by which this happens is that designers sketch ideas, and look for weaknesses in the sketch to understand weaknesses in the idea. So, designers must be able to take ideas that had a weakness, and turn it into a good design over time and with more drafts. Thus, B is correct.