A、5 years old. B、10 years old. C、7 years old. D、16 years old. A细节考核题，文章中出现过两次5years old。第一处：Education is free for all children

Education is important in England. English children are required to attend school until they are 16 years old. Education is free for all children from 5 to 18. About 94 per cent of pupils in the UK receive free education from public funds, while 6 per cent attend independent fee paying schools.
    All government--run schools, state schools, follow the same National Curriculum. The school year is 39 weeks long and is divided into three terms, the autumn term, the winter term and the spring term.
    Most children start school when they are 5. At the age of 11, they move on to regular high schools, known as secondary schools.
    English children are required to attend school until they are 16 years old. At the age of 16, students write an examination called the GCSE (General Certificate of Secondary Education). All students are tested in mathematics, English literature, English composition, science, history or the Classics, one modern language, and one other subject, such as art or computer studies.
    After completing the GCSE, some students leave school, others continue at high school or college, for two more years and take a further set of standardized exams; known as A levels. These exams determine whether a student is eligible for university.