A、Because he could have more spare credits. B、Because the 15-credit-plan was more cost-efficient. C、Because he had to make up 15

M: Hi Stacy.
W: Oh, hi Mark.
M: How was your summer vacation?
W: I worked over the summer at a restaurant. Have to make tuition money, right? What did you do?
M: I took summer school. I withdrew from two of my classes last year, so I wanted to make them up.
W: So are you officially a junior now?
M: Yeah. And I have 5 credits to spare. I only needed to take 10 credits over the summer, but I took 15 because the price was the same.
W: That makes sense. So where is Nicole?
M: She dropped out of school completely.
W: Really? Why?
M: She worked at a startup company as an intern and since the business did well, they asked her if she wanted to work full-time.
W: Wow. She’s so lucky. She doesn’t have a degree and she already has a job.
M: It sounds good now, but I’m traditional. I want the degree, so I wouldn’t have accepted the offer.
W: Do you know how much they are paying her?
M: I don’t know. But I bet it must have been a good offer, or she wouldn’t have accepted it.
Q10: Why did the woman work in the summer vacation?
Q11: Why did the man take 15 credits instead of 10?
Q12: Why did Nicole drop out of school completely?