单选题 On Friday, a sociologist from the University of New Hampshire, Murray Straus, presented a paper at the International Conference on Violence, Abuse and Trauma, in San Diego, suggesting that corporal (身体的) punishment does leave a long -lasting mark -in the form of lower IQ. Straus, who is 83 and has been studying corporal punishment since 1969, found that kids who were physically punished had up to a five - point lower IQ score than kids who weren't - the more children were spanked, the lower their IQ--and that the effect could be seen not only in individual children, but across entire nations. Among 32 countries Straus studied, in those where spanking was accepted, the average IQ of the survey population was lower than in nations where spanking was rare, the researcher says.
According to Straus, physical punishment leaves a permanent mark on the child

• A. in the form of a lasting scar on the body.
• B. in the form of lower IQ.
• C. in the form of mental disorder.
• D. in the form of violence inclination.