直流输电的应用主要在（）。

A.远距离大容量送电

B.电力系统联网

C.直流电缆送电

D.现有交流输电线路的增容改造

On Feb. 17, 2009, it could snow all across America. Not outside, but in living rooms, on TV sets. That’s the date when broadcasters will switch to digital transmission, rendering millions of standard analog TVs useless. Consumers can avoid this whiteout, but only if they’re prepared. And there’s the challenge: How to inform the roughly 20 million households relying exclusively on analog sets that pull in their reception for free, through rabbit ears or a rooftop antenna. Analog TVs that receive cable or satellite will not be affected.
Consumers who own these sets don’t necessarily need to know why the federal government is mandating the change (to free up the airwaves for other purposes, such as wireless and public safety communications-though added benefits are better pictures and more channels). But they do need consistent and unbiased information on what to do and they need to be able to act on it. With fewer than 18 months to go, though, 56 percent of viewers with analog sets have never even heard of the switch. The General Accountability Office, the government watchdog, is concerned that with two government agencies involved, "no one is in charge."
The Federal Communications Commission is worried, too. "If we don’t do a better job of planning, we’ll have one of the biggest outrages Congress has ever seen," FCC commissioner Jonathan Adelstein told US senators last month. The options for consumers are fairly straightforward. Starting with the least expensive one, they are:

• a) buying a converter box using government coupons’
• b) subscribing to cable or satellite TV services, which will make the transition on their end, or
• c) buying a digital TV. But sharing this information is anything but simple. Because it has only $ 5 million to get the message out, the government is turning to the private sector for help with public-service announcements and educating consumers in stores. This partnership makes sense, if done right. Certainly, the broadcasting industry wants viewers to keep on watching, However, there’s a danger in their self-interest. Naturally, retailers also want people to buy new digital televisions instead of opting for low-cost converters, and cable and satellite providers want new subscribers. And industry may not have enough of a financial incentive to reach out to certain analog viewing groups, such as the poor or elderly (seniors make up 40 percent of analog households).
  Other serious issues remain. One is whether the converter boxes will be uniformly available in stores. Beginning in January, households should be able to apply to the Commerce Department’s National Telecommunications and Information Administration for up to two $ 40 coupons to offset the costs of converter boxes expected to be priced from $ 50 to $70. But some retailers may not stock the boxes if they don’t have much demand for them.
  And what about recycling analog televisions, of which there are an estimated 70 million More than anything, what’s needed is oversight and coordination of the conversion. Congress should designate one of the two government agencies involved in this project to take the lead, or empower an independent group to oversee the transition.

Explain the statement "However, there’s a danger in their self-interest. " (para. 3)