Why save endangered species? For the general public, endangered species appear to be little more than biological oddities. A very different perception is gained from considering the issue of extinction in a wider context. The important point is that many major social advances have been made on the basis of life forms whose worth would never have been perceived in advance. Consider the impact of rubber-producing plants on contemporary life and industry: approximately two-thirds of the world's rubber supply comes from rubber-producing plants and is made into objects as diverse as rubber washers and rubber boots.

23. The author's point is made chiefly by

(A) acknowledging the validity of two opposing points of view
(B) appealing to the emotions of the audience rather than to their intellects
(C) suggesting a useful perspective for viewing the question raised at the beginning of the passage
(D) trying to discredit the view of an opponent without presenting an alternative hypothesis
(E) generalizing from similar to dissimilar cases



24. All of the following facts could be used as illustrative examples in addition to the example of rubber-producing plants EXCEPT:


(A) The discovery of the vaccine for smallpox resulted from observing the effect of the cowpox virus on the hands of dairy workers.
(B) The major source of our pharmaceutical supplies is plants, some of them commonly thought of as weeds.
(C) Certain antibiotics were originally derived from mold growing on cantaloupe.
(D) Plastic is a unique product derived from petroleum and petroleum by-products.
(E) Hamsters and other rodents have played an important role in laboratory tests of medicine for use on humans.