【正确答案】 B

【答案解析】[听力原文]
The high-tech company Google has a fleet of self-driving cars, by August they have logged 480,000 kilometers. Major auto manufacturers in the United States and Europe are also working on the technology for autonomous vehicles. Volvo is doing road tests and says it plans to sell driverless cars by 2020. In September, California Governor Jerry Brown signed a bill to allow autonomous vehicles on the roads of his state. Today we're looking at science fiction becoming tomorrow's reality, the self-driving ear. The technology for these cars includes cameras, radar and motion sensors. The systems have been improved through competitions sponsored by the US government agency DARPA, the Defense Advanced Research Projects Agency.