Which of the following is trueA．Only some students

单项选择题

In the United States, boys and girls start school when they are five years old. In some states they must stay in school until they are sixteen. Most students are seventeen or eighteen when they graduate from high school.
Most children go to public schools. The parents don"t have to pay for their children"s education. If a child goes to a private school, his parents pay the school for the child"s education.
Today half of the high school graduates go on to colleges. A student at a state college doesn"t have to pay much if his parents live in that state. Private colleges are expensive, however. About half of the college students in the United States work while they are studying. When a student"s family is not rich, he has to earn money for part of his college expenses.

Which of the following is true

A．Only some students leave school when they are eighteen.
B．It is cheaper to study in state colleges if the students" parents live in the state.
C．The parents usually pay all for their children"s education even they are not so rich.
D．Few college students work in the United States.