Read the following passage on transport, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50.

    (1) Increasing numbers of parents in the U.S. are choosing to teach their children at home. In fact, the U.S. Department of Education has estimated that in 1999, about 850,000 children were being homeschooled. Some educational experts say that the real number is double this estimate, and the ranks of homeschooled children seem to be growing at the average rate of about eleven percent every year.

    (2) At one time, there was a theory accounting for 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 own children at home due to their 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 students. The children are, therefore, deprived of the attention they need. Escalating classroom violence has also motivated some parents to remove their children from school.

    (3) Although there have been a lot of arguments for and against it, homeschooling in the U.S. has become a multi-million dollar industry, and it is growing bigger and bigger. There are now plenty of websites, support groups, and conventions that help parents protect their rights and enable them to learn more about educating their children. Though once it was the only choice for troubled children, homeschooling today is an accepted alternative to an educational system that many believe is failing.

This estimated number was presented by _____.