A、Robbery. B、Delinquency. C、Stealing. D、Premature sexual activity. DWhat is the unproductive behavior mentioned in the passage c

The most surprising trend is the increasing use of illegal drugs, tobacco, and alcohol among youth. Children who use these substances increase the chance of acquiring life-long dependency problems. They also bring about greater health risks. Every day, three thousand children begin smoking cigarettes regularly; as a result, a third of these youngsters will have their lives shortened.
    According to a study conducted by Columbia University on Addiction, children who smoke marijuana are 85 times more likely to use cocaine than ordinary people who never tried marijuana.
    The use of illegal drugs among eighth graders is up 150 percent over the past five years. While surprisingly high, the prevalence of drug use among today’s young people has returned to near-epidemic levels of the late 1970s. The most important challenge for drug policy is to change these dangerous trends.
    Early drug use often leads to other forms of unhealthy and unproductive behavior.  According to some survey, experts believe that illegal drugs are associated with premature sexual activity.
    In 1995, 10.5 percent of all youngsters between twelve and seventeen years of age used illegal drugs on a past-month basis. This rate has risen notably compared to 8.2% in 1994, 5.7% in 1993, and 5.3% in 1992—the historic low in the trend since the 1979, high of 16.3%. The University of Michigan’s 1996 Monitoring the Future study found that more than half of all high school students use illegal drugs by the time they graduate. So now the illegal use of drugs by youngsters has become a big problem in the United States.