听力原文：W: Well, it's sort of attractive, but in the end I still find it a pretty depress

M: Do you？ Why？

W: The animals are out of their natural environment. They're just here for humans to look at. There's nothing natural about it.

M: Yeah, but if we didn't have any zoos, a lot of species would just, well, they'd face extinction.

W: Do you really believe that？

M: Well, don't you？ I mean they have good breeding projects for some species that are dying out. Um, anyway, I think, there's a trend towards developing zoos to become education centers, stimulating information for kids and displays, and that kind of thing.

W: What we need to do is to take care of the natural environment, make sure that they've still got a place where they can live in the wild.

M: Well, yeah, OK. But it's just not happening, is it？ I think in reality you've got to have zoos.

W: Well, I just can't agree with that. I mean, what is the pleasure in watching animals pacing up and down in cages？

M: Look, zoos are changing. Some older zoos put animals in cages, but what about safari parks？ The animals are fine there. They've got a lot of space and people see them in a much more natural setting.

W: Well, maybe you're right.

What are the man and woman talking about？

A．About the building of the zoo.

B．About the lay-out of the zoo.

C．About the function of the zoo.

D．About the attractiveness of the zoo.