单选题 Speaker A: I'm going to the park with some friends for a barbecue on Sunday. Would you like to join us?
Speaker B: ______
A. Why not on Saturday? You see, I have an important appointment on Sunday.
B. Thanks, but unfortunately I have to take my sister to the airport on Sunday.
C. That's a wonderful idea. Barbecue is one of my favorites.
D. What preparation do you expect me to do for the barbecue?