A、To stop climate change. B、To find energy to replace oil. C、To find out the real problem. D、To fight against drought and floods

W: Have you seen the news about the forest fires in the States? I think it shows the threat of global warming—which is going to be a big problem.
M: There is also flood damage which is something that we’re seeing now, in different parts of the world. And the opposite, of course—drought conditions as well.
W: Well, that used to just be in Africa but I think these days we’re more worried about it in Europe—I mean, (19)do you remember that thing a few years ago when all those people died in the heatwave?
M: Of course. What about air pollution, which is obviously on the minds of many politicians at the moment, that’s going to affect us perhaps more in the long term than now.
W: Well it already does, doesn’t it? Think about how many more people there are now with allergies and skin problems.
M: Very true—and fossil fuel consumption.
W: Not to mention the price of oil these days. So, which one do you think is going to be the biggest threat?
M: I think it’s going to be drought conditions in the short term and(20)air pollution perhaps in the longer term.
W: You could be right. Maybe either drought or floods—one of the two related to climate change.(21)And I think we really do need to find an alternative to oil—that’s going to be a real problem.
19. Q: What happened in Europe a few years ago?
20. Q: According to the man, what will be the biggest threat in the long term?
21. Q: What does the woman think we need to do?