A、Teleconferencing. B、Airmail. C、Railway traveling. D、Faxing. A由原文可知，男士认为远程会议和即时邮件可以减少商务出差。因此答案为A。

M: Good morning, Faith. In light of (根据，鉴于) the recent economic downturn, we thought we should think about some ways we can conserve energy.
W: I think we could easily cut down on "vampire power". Our computers and other electronic devices actually continue to suck power, even when they are switched off.
M: Good one! The online encyclopedia Wikipedia claims that "vampire power" or "stand by power" is responsible for using as much as 10 percent of electricity consumption.
W: We could unplug (拔去……的插头) the equipment or put in power strips that can completely turn off power.
M: Just imagine, we could save 10 or 15 percent on our energy bill just by unplugging our computers!
W: And that’s just the beginning! You see these lights above us? These use LED bulbs that are 10 times more efficient than the bulbs you are using in the rest of the office.
M: But they’re pretty pricey (昂贵的), aren’t they?
W: Yes. They cost more, but you’ll find that they pay for themselves.
M: I’ve got one that will require a bit of sacrifice. We really don’t need to use bottled water for meetings. We could also get rid of paper cups for the water cooler and everyone could use their own mugs (杯子) instead.
W: Ah, I love bottled water, but I agree that your idea is certainly more environmentally friendly.
M: Yep. Sometimes going green does require that we change our mindset. It’s funny how many of us are very conscientious at home. We recycle and reuse, but when we get to the office, we sometimes become very wasteful.
W: I’ve recently noticed how much paper I use on a daily basis and I’ve been trying to cut down. I’ve found that I actually very rarely need to print emails. Also, by utilizing my fax modem, I don’t ever need to print a hard copy (复印件) for faxing.
M: That’s going to add up! In the end you’ll find it makes a huge positive difference!
W: But you know, even with all these good ideas and strategies, I feel like it counts for nothing when you factor in (考虑进来) air travel. Our people make a lot of international trips each year and flying puts tons of carbon dioxide into the atmosphere.
M: Ah! Good point! Well, for starters, with teleconferencing and instant email one would hope business travel be reduced.
W: But sometimes we have no alternative. We have to check out factories and locations in some countries; you really have to look the person in the eye and physically shake his hand.
M: This is true. Anyway, we’ve got a lot so far. Nice talking with you.
W: Me too. I hope it will help a lot in the future.
M: I’m sure it will.
6. What does Wikipedia say about "vampire power"?
7. What does the woman say about LED bulbs?
8. What does the man imply by mentioning people’s different behavior at home and in the office?
9. How does the woman plan to save paper?
10. Which is a substitution for air travel according to the man?