A、A vacation trip to Yellowstone Park. B、A lecture by a visiting professor. C、Her biology thesis. D、A research project. D

M: Thanks for stopping by, Betty. I’d like to talk to you about a research project I thought you might be interested in. A friend of mine is working at Yellowstone National Park this summer...
W: Yellowstone! I’ve always wanted to spend some time out in Wyoming.
M: Wait till you hear what the project is... She’s working with the buffalo population. The herds have been increasing in size lately, which is good in theory...
W: Yeah...but I thought they were in danger of becoming extinct.
M: Well, apparently, because of all the winter tourists, paths are created in the snow. More buffalo are surviving the harsh winters because the paths make it easier for the buffalo to move around and find food. But it turns out that some of the herds are infected with a bacteria.
W: Oh yeah, I heard about that. Bru...
M: Brucella abortus.
W: Right, it’s been.around for quite a while.
M: Yes, it has. And because the buffalo population is increasing, they’ve been roaming more than usual, the disease has begun to spread to the cattle ranches that border the park.
W: That’s bad news! Isn’t that the disease that causes animals to abort their young?
M: Yes, and it’s caused a lot of controversy. Some of the ranchers even want to destroy the buffalo herds.
W: That’s awful! Have they made much progress with the research?
M: So far, they’ve been collecting tissue samples from dead buffalo to see if the bacteria’s present.
W: I’d really be interested in working on this. You know, I’ve been researching diseased animal populations...
M: That’s why I thought of you... I took the liberty of mentioning your name to my friend. She’s hoping you’ll be able to spend the whole summer out there.
W: Well, I was going to work on my thesis a lot in July, but I’m sure my adviser wouldn’t want me to pass up this opportunity.
27. What does the professor want to talk to Betty about?
28. According to the professor, why is the buffalo population increasing?
29. Why does the professor think Betty would be interested in going to Yellowstone?
30. How will Betty probably spend the summer?