题目内容：

Social norms of right and wrong are vital to a well-functioning society. However, such moral standards are changeable and the psychological mechanisms(机制) driving this change are unknown. Now, researchers at Karolinska Institute report that our view of selfish and unselfish behaviors changes depending on how common they are.

The results are based on a combination of behavioral experiments, mathematical models and computer simulations. In the experiments, the participants first observed other people's behavior in a so-called "public goods game," in which players receive a sum of money and then choose either to invest it to varying degrees so that it benefits everyone in the group, or to keep it for themselves. After every round, the participants were asked to judge the different choices as morally right or wrong, and whether the choices ought to be punished with a reduction in how much the players gained.

Unselfish behavior was considered more morally right than selfish, but both behaviors were judged to be more moral and less deserving of punishment if the majority exhibited them than if they were uncommon. The commonness of the selfish behavior also affected the participants' willingness to themselves pay to punish selfishness.

"Tolerance of selfish behavior increased when the majority of the players kept the money for themselves, which surprised me," says principal investigator Andreas Olsson, senior lecturer at Karolinska Institutet's Department of Clinical Neuroscience. "The fact that a behavior is common doesn't automatically mean that it's right -- this idea is based on faulty logic that confuses facts with moral values."

The study shows our view of what is morally right and wrong has strong similarities with social conformity, in that we tend to adapt ourselves to the people around us and how they behave. This means that changes in our social environment can quickly alter our moral compass.

"This is interesting from several angles, and could explain why moral attitudes change over time, such as those towards public goods or legality," says Björn Lindström, postdoc at University of Zürich and Karolinska Institutet's Department of Clinical Neuroscience.

1.According to Andreas Olsson’s analysis, if people accept selfish behavior, they actually________.

A. get facts and moral values mixed up    B. misunderstand social mechanisms

C. follow the logic of their own    D. consider it correct and reasonable

2.It can be concluded that the participants in the experiments are punished if _________.

A. they can’t play "public goods game"

B. invest the money to benefit group members

C. they behave differently from the majority

D. they keep the money for themselves

3.According to the passage, what is morally right or wrong is shaped by the following Except________.

A. the way people around us behave

B. changes in our social environment

C. personal standards of values and attitudes

D. how widespread a particular behavior is

4.Which of the following might be the best title of the passage?

A. The psychological mechanisms behind attitude change

B. Behavior is considered more moral the more common it is

C. Our view of selfish and unselfish behaviors

D. Moral standards of selfish and unselfish behaviors