Given the question: Read the article and select the best answer. Article: In the last few years, some researchers have decided to study why kids lie ,So they made up a special team of 12 students, all under the age of 21. Each student was given 36 cards, and each card listed a topic that teens sometimes lie about to their parents, The researchers worked through the cards with the teens, learning what things the kid was lying to his parents about, and why. By the end of the interviews, the kids saw for the first time how much they were lying and how many of family's rules they had broken. It was reported that 98% of the teens had lied to their parents. Out of the 36 topics, the average teen was lying to his parents about 12 of them. The teens lied about what movie they went to, and whom they went with .They lied about how they spent their afternoons while their parents were at work, and something like that. Most parents hear their child lie and think he's too young to understand what lies are or that lying is wrong. They believe their child will stop when he gets older. Many books also advise parents to just let lies go -- they'll grow out of it. But the truth is that kids grow into it. In studies where children are observed in their natural environment, a 4-year-old child will lie once every two hours, while a 6-year-old child will lie about once every hour and a half. Question: The researchers started the project by _ . Options: A: playing cards B: free talking C: doing a survey D: discussion
The answer is:
C