D

If it were only necessary to decide whether to teach elementary science to everyone on a mass basis or to find the gifted few and take them as far as they can go, our task would be fairly simple. The public school system, however, has no such choice, for the two jobs must be carried on at the same time. Because we depend so heavily upon science and technology for our progress, we must produce specialists in many fields. Because we live in a democratic nation, whose citizens make the policies for the nation, large numbers of us must be educated to understand, to support, and when necessary, to judge the work of experts. The public school must educate both producers and users of scientific services. In education there should be a good balance among the branches of knowledge that contribute to effective thinking and wise judgement. Such balance is defeated by too much emphasis on any one field. This question of balance involves not only the relation of the natural sciences, the social sciences, and the arts but also relative emphasis among the natural sciences themselves. Similarly, we must have a balance between the current and classical knowledge. The attention of the public is continually drawn to new possibilities in scientific fields and the discovery of new knowledge; these should not be allowed to turn our attention away from the sound, established materials that form the basis of courses for beginners.

According to the passage, the task of education is fairly complicated because ______.