How do paragraphs 18-20 contribute to the development of the theme?
A. They illustrate that the people do not know what will result from their actions.
B. They demonstrate how dangerous the hole is to human life and why it must be
filled.
C. They give an example of how changes in the environment can positively affect
human beings.
D. They show how people that live in close contact with nature are better able to
understand natural changes.
(18)The scientist contacted people at his laboratory and had them bring out a high-powered bull horn, with
which he was going to check out the echo from the hole’s bottom. He tried switching through various
sounds, but there was no echo. The scientist was puzzled, but he could not very well give up with
everyone watching him so intently. He put the bull horn right up to the hole, turned it to its highest
volume, and let it sound continuously for a long time. It was a noise that would have carried several
dozen kilometers above ground. But the hole just calmly swallowed up the sound.
(19)In his own mind the scientist was at a loss, but with a look of apparent composure he cut off the sound
and, in a manner suggesting that the whole thing had a perfectly plausible explanation, said simply,
“Fill it in.”
(20)Safer to get rid of something one didn’t understand.