单选题 The example given in the passage implies that ______.

A、 participation in interesting activities relating to a subject improves one’s achievement in that area
B、 school principals do more than their share in interpreting the curriculum to their parents
C、 only a small part of the school day should be set apart for drilling in arithmetic
D、 teachers should occasionally make home visit to parents

【正确答案】 A

【答案解析】作者在第五段对文中例子进行了总结“his son is making satisfactory progress in mathematics，and at the same time，enjoying the work”，可见[A]为正确答案。