A、He is a scientist. B、He works at a television station. C、He is a doctor. D、He is a college student. D

M: Hi, Jane! Did you watch that documentary on TV last night?
W: No, I was in a meeting, and didn’t get home until 11:50. What was it about’?
M: It was about insects.
W: Insects?
M: Yeah! Do you know they are the most successful creatures on the planet?
W: What, more successful than humans?
M: Well, think about it! They were around long before people were--there are far more insects than humans--I mean, trillions of them! And they are reproducing all the time!
W: Well, I suppose that’s true!
M: And they are incredibly adaptable.
W: In what way?
M: Well, take mosquitoes for example. You know, they spread malaria. Malaria is still a big problem in the world. The trouble is that every time we try to wipe out the mosquitoes with some new insecticide, they change their body-chemistry!
W: Haven’t the scientists just brought out a new insecticide to fight mosquitoes?
M: Yes, they have. But I bet that within five years the mosquitoes will simply adapt again!
W: I suppose it keeps the scientists employed!
M: Yes! You know, I’d really like to work in that field after I graduate.
W: Why not!