A、A radio program. B、A popular book. C、A TV program. D、Big Brother. C短文中提到，另外一个真人秀节目叫做《幸存者》，这一节目的创意来源于1997年在瑞典创办的一个电视节目。

Almost anything can be the topic of a reality show.(18)"Big Brother" is one of the most popular reality shows, in which a group of people, moved into a house together and were filmed 24 hours a day for three months. These people, who are all strangers, live together, eat together, and share bedrooms. They are isolated from the outside world, while people at home watch them all on TV.(19)The show started in Netherlands in 1999. Soon other countries started their own versions of "Big Brother," and the show became popular all over the world. Another popular reality show is called "Survivor."(20)The idea came from a TV show made in Sweden in 1997. The show leaves a group of ordinary people in a place far away, such as an island or a desert. The people have to find their own food, make fire to keep themselves warm, build their own places to sleep, and participate in difficult challenges. Each week, the participants choose one person to leave the show. The last person left is the winner and wins one million dollars. Today, people in over 20 countries around the world watch to see who will be the survivor!
18. How long do the volunteers in "Big Brother" stay together?
19. When did "Big Brother" start?
20. What does the idea for "Survivor" come from?