Read the following passage and mark the letter A, B, c, or D to indicate the correct answer to each of the questions.
One of the biggest trends in television in recent years has been the rise of “Reality TV”. These shows, in which ordinary people are placed in unusual situations and then filmed without a script, have become some of the highest rating shows on television. Early programs of this genre, including Big Brother (from the Netherlands) and Survivor (from the United States), have led to dozens of copycat programs in many different countries. A common element to many of these programs is that a number of contestants are placed in a closed environment in 
they are filmed 24 hours a day, and every week contestants are thrown off the show. What is it about these shows that makes them so popular? Perhaps it is because viewers enjoy watching ordinary people with real emotions being placed in extraordinary, situations. Or perhaps it is that people are really voyeurs - they enjoy being a spy, looking secretly into other people’s lives.
Question: The underlined word ‘‘which” in the passage refers to_______.