A caring mother is the single most important factor in preventing teenagers from abusing drugs and alcohol,researchers said on Friday.An international study showed that teenagers living with both parents are less likely to suffer from alcohol and drug problems,and a strong is the most effective way to fight against them. "These findings suggest that living with both parents may prevent drug use."said Dr.McArdle,of Newcastle University in northern England, who led the study."They also suggest that attachment ,particularly to mothers,is a more effective factor and that this is truly across cultures and substances."The report, which is published in the journal Addiction, involved nearly 4,000 teenagers in England,Ireland,Italy,Germany and the Netherlands.They were questioned about their use of several kinds of drugs and alcohol.The teenagers also filled in questionnaires about their relationship with their parents and grandparents, how well they were supervised after school and whether they were allowed to meet friends at home. "Both the quality of family relationships and the structure of families have significant influences on youth drug use," McArdle said in a statement.But he added that a strong offered the greatest protection against developing drug habits.The rate of drug abuse among teenagers living with both parents and who had a good relationship with their mother was 16.6 percent.If either factor was missing, the drug abuse rate rose to 32 percent.More than 42 percent of teenagers living in one parent families who did not have a strong bond with their mother used drugs. Drug prevention campaigns in British schools and on television warn teenagers about the danger of drugs and alcohol but McArdle said no one is dealing with the problem of their parents' responsibility Which of the following is NOT mentioned in the passage   _   ?
Teenagers with both parents won't have the drug use problem. Teenagers from several countries filled in the questionnaire. Teenagers were asked about their relationship with parents. Teenagers in British schools are warned against drugs abuse.