题目内容：

Research shows that humans switch from selfish to unselfish behaviour when they are watched. Do you?

A picture of a set of eyes on a computer screen can cause a change in the way people act. Even images of eyes on a charity donation, collection box encourage people to be unselfish, because people put more money in a collection box that has a picture of eyes on it than they do when a flower symbol is on the box.

Manfred Milinski from the Max-Planck Institute for Evolutionary Biology in Germany and Bettina Rockenbach of the University of Berlin, the authors of a new study, found that people act better when they are being watched because they feel they will be rewarded for good behaviour. Their report also referred to other research showing that this response of behaving well when watched is somehow coded into humans and people respond this way unconsciously, or without realizing it.

It is not just humans that act unselfishly when they are being watched. A fish called the grooming fish cleans other fish. When other fish are around, it is gentler. When no other fish are around, however, the grooming fish bites chunks from the fish it is supposed to be cleaning.

The researchers suggest that the best way to get people to behave in the correct way is to make them feel watched. This could be the reason for the success of a famous American army poster. On it was a picture of an elderly man staring fiercely and pointing, it appeared, to the person who was looking at the poster. Under the picture was the caption 'I Want You' It encouraged hundreds of thousands of young American men to join the army during the Second World War to fight the Germans and Japanese.

1.According to the report, why does a person behave better when he feels he is being watched?

A. He does not want to be shamed by others.

B. He needs to show he is a good person.

C. He desires others to like him more.

D. He feels he will receive some social reward.

2.What is the text mainly about?

A. It describes changed behaviour when observed.

        B. It details ways to control people's behaviour.

         C. It tells how to make people work harder.

       D. It discusses different advertising methods.

3.Where would the study described in the text most likely be found?

         A. In a newspaper.                                   

B. In a scientific journal.

         C. In an advertising magazine.                     

D. In a science textbook.