Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.

Earth is the only space we know of in the universe that can support human life, (26) ______ human activities are making the planet less fit to live on. As the Western world carries 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 very resource we have by (27) ______ all people can survive and prosper.

Everywhere fertile soil is (28) ______ built on or washed into the sea. Renewable resources are exploited so much that they will never be able to recover completely. We discharge pollutants into the atmosphere without any thought of the consequences. As a (29) ______ the planet's ability to support people is being reduced at the very time when rising human numbers and consumption are making increasingly heavy demands on it. The Earth's natural resources are there for us to use. We need food, water, air, energy, medicines, warmth, shelter and minerals to keep us fed, comfortable, healthy and active. If we are sensible in how we use the resources, they will last indefinitely. But if we use them (30) ______ and excessively they will soon run out and everyone will suffer.