Given the question: Write a multi-choice question for the following article: Article: Studies have documented that smiling is a universal and effective way to lift mood. But in the latest research on the power of the smile, researchers led by Marcus Munafo of the University of Bristol in England found that even seeing smiles on the faces of others can have a profound effect on a person's tendency toward violence or aggression -- that is, as long as that person recognizes the smile as one of happiness, and not as a sneer . Munafo and his colleagues conducted a series of experiments involving normal adults and highly aggressive teens referred to a youth program, either by educational authorities or the courts. About 70% of the teens already had a criminal record. In the first experiment, 40 healthy adults, aged 1830, looked at facial expressions on the computer ranging from happy to angry with increasingly difficult ones to _ in between. Participants were asked how angry they felt and then had to rate the images as displaying either happiness or anger -- there was no option for "unclear" or "unable to tell". From these ratings, the scientists could generate a score of their preference toward happiness or anger. Previous research found that aggressive people -- including violent offenders -- tend to consider even a common expression as an unfriendly one. "You looking at me?" can easily turn a simple question into a tragic fight. Based on their original scores, half of the participants were then told by the computer that some of the unclear faces that they had rated as angry should have been scored as happy. This was intended to guide them toward judging the inbetween faces more positively. The other 20 received feedback that simply proved their first choices, creating a control group. After this training, both groups were tested again and the group that received the biased feedback shifted its ratings of unclear faces toward the happy side. Participants were also asked to rate their level of angry feelings again after completing the second round of testing. Those who were trained to consider...
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Question: According to Munafo's research, the anger and violent behavior in some youths resulted from _ .Options:A their misunderstanding of facial emotions of othersB their lack in knowledge of emotion recognitionC their inborn tendency toward violence or aggressionD their experience of being offended by others on purposeAnswer:A