F: Tina is about 20 now, isn't she? ,M: But I'm sure that she celebrated her twentieth birthday last year.
(A) F: So, you mean you are sure that she celebrated her eighteenth birthday last year, and now Tina is 19. (B) F: Really? Tina is 21 now? (C) F: OK, I see. Tina is 20 now because you are sure that she celebrated her nineteenth birthday last year. (D) F: I’m sorry, I didn’t understand. Could you repeat a little louder, please?
B