M: Hi, Sue, where have you been?
W: Oh, Hi, Dan, I was just at the library. I have to hand in my biology paper tomorrow.
M: Tomorrow? Oh, no, I thought it wasn' t due till Monday.
W: Oh. Don' t worry. It is due Monday. But I' m going away for the weekend and won' t be back till Monday night.
M: Oh, where are you going?
W: California. We' re having a family party.
M: Wow. That's great.
W: Yes. So have you started working on your biology paper?
M: Yeah. I'm doing it on bees and how they're able to recognize whether another bee is related to them.
W: How can they tell?
M: They use their sense of smell. The sweat bees guard their nests this way. If another bee approaches the nest, the guard determines if the new bee is familiar. If it is, it' s allowed to enter.
W: Interesting topic! Can we talk about it next time when you finish it?
M: Of course! And have a nice weekend with your family!
W: Thanks! See you!
M: See you!
What is the relationship between the speakers?
综合推断题。由一开头男士与女士的对话可知，两人在谈论他们马上要交的论文，可知两个人是在学业上有关的关系，选项中的四种关系中只有同学与学习有关．故选C。