If there is no difference in general intelligence between boys and girls, what can explain girls’ lack of success in science and mathematicsIt seems to be that their treatment at school is a direct cause. Mathematics and science are seen as mainly male subjects, and therefore, as girls become teenagers, they are less likely to take them up. Interestingly, both boys and girls tend to regard the "male" subjects as more difficult. Yet it has been suggested that girls avoid mathematics courses, not because they are difficult, but for social reasons. Girls do not want to be in open competition with boys, nor do they want to do better than boys because they are afraid to appear less ladylike and attractive.However, if we examine the performance of boys and girls who have undertaken mathematics courses, there are still more high-achieving boys than there are girls. This difference appears to be worldwide. Biological explanations have been offered for this but there are other explanations too.Perhaps the difference which comes out during the teenage years has its roots in much earlier experiences. From their first days in nursery school, males are encouraged to work on their own and to complete tasks: this is essential behavior for learning how to solve problems later on. Evidence shows that exceptional mathematicians and scientists have not had teachers who supplied answers.Apart from that, there can be little doubt that teachers of mathematics and science expect their male students to do better at these subjects than their female students. They even appear to encourage the difference between the sexes, not consciously, but they still do it. Such male-oriented teaching is not likely to encourage girls to take many mathematics and science courses, nor is it likely to support girls who do. It seems certain, then, that where these subjects are concerned, school widens the difference between boys and girls. In what way can students be best trained in mathematics and science（）

A. Male students are expected to do better than female students.
B. They are encouraged to work on their own and to complete tasks.
C. They are always supplied with answers.
Difference is encouraged between the sexes unconsciously.