The interviewer's tone completely changed after I answered her first question about what I know about the company. She was no longer keen on continuing to interview me just because of the one-sentence response I gave, and it was not an offensive response by any means. I also did not use any informal language. I admit that I could have prepared myself better for the interview, but I feel like the fact that she did not continue interviewing me because of this one mistake I made is rather unfair.