Increasing numbers of parents in the U.S. are choosing to teach their kids at home. In fact, the U.S. Department of Education estimated that, in 1999, around 850,000 children were being homeschooled. Some educational experts say the real figure is about double this estimate, and the ranks of homeschooled children appear to growing at a rate of about 11 percent annually.At one time, there was a stigma associated with homeschooling. It was traditionally used for students who could not attend school because of behavioral or learning difficulties. Today, however, more parents are taking on the responsibility of educating their children at home due to dissatisfaction with the educational system. Many parents are unhappy about class size, as well as problems inside the classroom. Teacher shortages and lack of funding mean that, in many schools, one teacher is responsible for thirty or forty pupils. The result is often that children are deprived of the attention they need. Escalating classroom violence has also motivated some parents to remove their children from school.Critics of homeschooling say that children who are not in the classroom miss out on learning important social skills because they have little interaction with their peers. Several studies, though, have shown that the home educated appear to do just as well in terms of social and emotional development as other students, having spent more time in the comfort and security of their home, with guidance from parents who care about their welfare. In spite of this, many critics of homeschooling have raised concerns about the ability of parents to teach their kids effectively. Many parents who homeschool have no teacher training and are not competent educators of all the subjects taught in schools. In terms of academic achievement, however, homeschooled children do just as well as those who have been in the classroom and many walk the campuses of Harvard and Stanford alongside the conventionally educated.With an increasing number of disgruntled parents taking their children out of class, schools are receiving less money in per pupil funding. Some see this as a threat to the system, and argue that schools will never be able to improve their situation and restore parents' confidence in the educational system. Many schools have opened their doors to homeschoolers on a part-time basis, allowing these children to attend classes once or twice a week, or take part in extracurricular activities such as playing football or taking ballet lessons. While parents will not completely put their confidence back into the system, many of them have reached a compromise that allows their children the extra benefits of peer interaction and access to a wider choice of activities.Whatever the arguments for or against it, homeschooling in the U.S. has become a multimillion dollar industry, and it is growing. There are now websites, support groups, and conventions that help parents assert their rights and enable them to learn more about educating their children. Though once the last resort for troubled children, homeschooling today is an accepted alternative to an educational system that some believe is failing. 1. What is the reason that more parents are taking on the responsibility of educating their children at home?
选项：

A:Teacher shortages and lack of funding.;
B:Escalating classroom violence.;
C:Large class and problems inside the classroom. ;
D:Dissatisfaction with the educational system.