The investor asks you a question, and the instinctive reaction of an entrepreneur is to fire back with data, slides, and arguments to prove that the investor is wrong. "No, that concern does not apply to me because, because. because". Part of the rhetoric includes a repeat of what just has been presented, to eliminate the possibility that the investor did not understand it the first time around. Boom, boom boom.
Pick your battles. Especially if the investor bases the question on 5 other startups she has seen in the same field, it is 5 people she knows and trusts against you she just met 20 minutes ago. Maybe she has a point, maybe you need to find out a bit more about the background of her concern, after which you can give a more balanced answer, which could well be, let me check and I will get back to you.
Read the human signals, if the investor does not engage anymore and says "OK, I understand", but her eyes say something different, it might well be that she simply does not want to hear a repetition of your arguments she does not believe.