I'm taking a test and have to guess the right answer to the question after the article. Article: The city can seem a cold, mean place. In the middle of so many people hurrying about their own business, a person can feel alone among the millions of others. There is a popular view that in cities, strangers are less likely to help an elderly person cross a street or call the police when they see a bike being stolen. Recently, a New Yorker named Casey Neistat did an experiment. He chained up his bike in several public places, then "stole" it in a number of obvious ways, such as using a hacksaw . He filmed everything to see whether other New Yorkers would try to stop a shameless bike theft. The result? People just walked on by. Is this evidence of an immoral, selfish urban society? Not necessarily. According to another recent study, the way city people mind their own business is about other factors besides morality . This is called the Bystander Effect, the theory that city people do not react because of the urban enviromnent they live in. Psychologist Dr. Harold explained why people did not involve themselves in Neistat's bike theft experiment with the Bystander Effect. First, people who live in cities are surrounded by so much activity that they stop noticing what is going on around them. Second, they are less easy to surprise and assume every activity has a logical explanation. "The third is that people notice it, but they don't know what to do," he continued. "And the fourth is fear -- they know they should do something, but they're afraid to challenge someone with a hacksaw." A lack of concern is only a small reason why people don't take action, concludes Dr. Harold. Despite the results of Neistat's experiment, there is also evidence of a sense of team spirit that connects people in cities. All it takes is a funny joke or a shared interest to start a conversation with someone at a bus stop. When city folk are in trouble, they come together for support -- famously in New York on City society is different, but that doesn't mean it's cold or mean -- it just means it's busy! Question: Casey Neistat fihned everything in the experiment with the purpose of _ . Options: A: proving that he was not the thief B: telling people that bike theft was immoral C: finding out who had a sense of right and wrong D: making his experiment well-known to the public
C