M: Barbara, could you cover for me for a few hours? ,F: I guess so, Sam. I could tell the boss you've gone to buy some office supplies if she asks.
(A) M: Thank you so much! You have returned me the favor and we don't owe each other now. (B) M: Excuse me, could you repeat the question? (C) M: Sorry, boss! I won't leave work again. (D) M: It is ok. I will explain to me colleagues later and thank you again for coming.
B