A、A scarcity of jobs in their field. B、Inadequate training in methods of biological research. C、Difficulties in classifying all

W: Hi. Bill, how is it going?
M: Oh, hi, Jane. I’m OK. How about you?
W: You can probably tell just by looking at me. I’m really busy. Hey, what are you reading?
M: A pretty interesting article. My biology professor assigned it, and I thought I just looked it over. But I got really involved in it. It’s about endangered species.
W: That sounds pretty interesting. I’m getting frustrated with the two research papers I’m struggling with. And can you believe they are both due on the same day?
M: That’s tough.
W: I’ll get through it. So what’s this you are reading?
M:(19)Well, it’s basically about the choices conservationists are faced with. You know, these days funding is so hard to come by.
W: Wait a minute. Is the focus on biology or economics?
M: Both.(20)Conservationists don’t have enough funding to save every endangered species in the world, so they have to decide based on what would be lost if a species became extinct.
W: Can you give me an example of what you mean?
M: Take for instance, two animals, the spotted owl and the tailed toad. The article says the toad is unique. It has no relatives. But there are a lot of varieties of owls.
W:(21)So, if that toad became extinct, we’d lose an important link in the chain of evolution, right?
M:(21)Exactly. But that isn’t so for the owl. So for conservationists, it might be a clear choice of which animal to save.
W: I see. I am glad I don’t have to make that kind of decision, aren’t you?
19. What are the speakers mainly discussing?
20. What problems do conservationists have?
21. What can be inferred about the tailed toad?