【正确答案】 B

【答案解析】[听力原文] 18-21
In the high mountain country outside the city of Toluker, there stands a prison. This prison is quite different from other prisons in the world. The guards, except for two at the main gate, are not armed. There are many remarkable things about Toluker prison. For example, of the 15,000 individuals who have been in prison at Toluker, less than two percent have got into trouble again with the law. Men in the open prison are free to find work on the outside but must go back to prison each night. On weekends they are allowed to go home. When most other prisons are still sending criminals back into society, Toluker is returning people who stand on their own feet and contribute to society. In 1974, a prison called Barb Grook moved to the open prison. A year later, he left Toluker for the last time. He was then nearly forty-six and had been in prison for fourteen years. He got a job as construction worker in the city, remarried and was they believed as a useful person of his community. If you ask Barb why Toluker works, he would say "because they believe in me when I was at my worst."

文中提到“men in the open prison are free to find work on the outside”，所以选B。