A、She had to go home. B、She was too tired to continue. C、She had to finish her schoolwork. D、She was thirsty. B

M: Hey, Karen. Looks like you got some sun this Weekend.
W: Yeah, I guess so. I spent the weekend at the beach.
M: Oh, yeah? That’s great. Where did you stay?
W: Some friends of my parents live out there and they invited me for as long as I wanted to stay.
M: So what are you doing back there already?
W: Oh, I have a paper I need to work on and I just couldn’t do any serious studying at the beach.
M: I don’t blame you. SO what did you do out there? I mean besides lying out in the sun obviously.
W: I jogged up and down the beach and I played some volleyball. You know, I never realized how hard it is to run on sand. I couldn’t even get through a whole game before I had to sit down. It’s much easier to run on the wet sand near the water.
M: Not to mention cooler. Did you go swimming?
W: I wanted to, but they said the water isn’t warm enough for that until a couple of months from now. SO I just waded in up to my knees.
M: It all sounds like relaxing. I wish I could get away to the beach like that.
W: It looks like you could use it. Don’t tell me you spent the weekend in the library again.