Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions.

In early days no medical college took a woman student. Elizabeth Blackwell, however, was determined to become a doctor. The young American wrote

again and again to a number of medical colleges, asking if she could be enrolled but each time the answer was NO.

Then one day, to her surprise, she got a letter from the dean of a college in Geneva, which said YES.

At first Geneva College, like the other colleges, was not willing to enroll Elizabeth. But later the important people of that college learned that Elizabeth's application had the support of a famous doctor, and they were afraid to offend that man.

So the dean decided to play a trick by turning the matter over to the student's general meeting of the college, thinking that the students would be the last to agree to take Elizabeth.

When the boy students met, most students took no interest in the matter. Of the rest, some considered the young American's idea interesting and some thought by having Elizabeth they would be proud of their college training the world's first woman doctor. Very soon the students all agreed to accept Elizabeth.

The dean of Geneva College was of course very sorry to learn this, but seeing that he could do nothing to keep Elizabeth out, he gave in.

We are learning that it is necessary to keep rivers clean if we want to enjoy the (27) _______of the natural resources.