Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that best fits each of the numbered blanks.

         Earth is the only place we know of in the universe that can support human life. (36)__________human activities are making the planet less fit to live on. As the western world (37)__________on consuming two-thirds of the world's resources while half of the world's population do so just to stay alive we are rapidly destroying the (38)__________ resource we have by which all people can survive and prosper. Everywhere fertile soil is (39)__________built on or washed into the sea. Renewable resources are exploited so much that they will never be able to recover (40)__________.We discharge pollutants into the atmosphere without any thought of the consequences. As a result the planet's ability to support people is being reduced at the very time when rising human numbers and consumption are make demands on increasingly heavy demands on it.

Điền vào số (38)