Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.
Peter and Mary are discussing life in the future.
- Peter: "I believe space travel will become more affordable for many people in the future." Mary: "____”
A. There's no doubt about that.
B. I am sorry to hear that.
C. It is very kind of you to say so.
D. It doesn't matter at all.